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Vincent Selhorst-Jones

Vincent Selhorst-Jones

Properties of Logarithms

Slide Duration:

Table of Contents

I. Introduction
Introduction to Precalculus

10m 3s

Intro
0:00
Title of the Course
0:06
Different Names for the Course
0:07
Precalculus
0:12
Math Analysis
0:14
Trigonometry
0:16
Algebra III
0:20
Geometry II
0:24
College Algebra
0:30
Same Concepts
0:36
How do the Lessons Work?
0:54
Introducing Concepts
0:56
Apply Concepts
1:04
Go through Examples
1:25
Who is this Course For?
1:38
Those Who Need eExtra Help with Class Work
1:52
Those Working on Material but not in Formal Class at School
1:54
Those Who Want a Refresher
2:00
Try to Watch the Whole Lesson
2:20
Understanding is So Important
3:56
What to Watch First
5:26
Lesson #2: Sets, Elements, and Numbers
5:30
Lesson #7: Idea of a Function
5:33
Lesson #6: Word Problems
6:04
What to Watch First, cont.
6:46
Lesson #2: Sets, Elements and Numbers
6:56
Lesson #3: Variables, Equations, and Algebra
6:58
Lesson #4: Coordinate Systems
7:00
Lesson #5: Midpoint, Distance, the Pythagorean Theorem and Slope
7:02
Lesson #6: Word Problems
7:10
Lesson #7: Idea of a Function
7:12
Lesson #8: Graphs
7:14
Graphing Calculator Appendix
7:40
What to Watch Last
8:46
Let's get Started!
9:48
Sets, Elements, & Numbers

45m 11s

Intro
0:00
Introduction
0:05
Sets and Elements
1:19
Set
1:20
Element
1:23
Name a Set
2:20
Order The Elements Appear In Has No Effect on the Set
2:55
Describing/ Defining Sets
3:28
Directly Say All the Elements
3:36
Clearly Describing All the Members of the Set
3:55
Describing the Quality (or Qualities) Each member Of the Set Has In Common
4:32
Symbols: 'Element of' and 'Subset of'
6:01
Symbol is ∈
6:03
Subset Symbol is ⊂
6:35
Empty Set
8:07
Symbol is ∅
8:20
Since It's Empty, It is a Subset of All Sets
8:44
Union and Intersection
9:54
Union Symbol is ∪
10:08
Intersection Symbol is ∩
10:18
Sets Can Be Weird Stuff
12:26
Can Have Elements in a Set
12:50
We Can Have Infinite Sets
13:09
Example
13:22
Consider a Set Where We Take a Word and Then Repeat It An Ever Increasing Number of Times
14:08
This Set Has Infinitely Many Distinct Elements
14:40
Numbers as Sets
16:03
Natural Numbers ℕ
16:16
Including 0 and the Negatives ℤ
18:13
Rational Numbers ℚ
19:27
Can Express Rational Numbers with Decimal Expansions
22:05
Irrational Numbers
23:37
Real Numbers ℝ: Put the Rational and Irrational Numbers Together
25:15
Interval Notation and the Real Numbers
26:45
Include the End Numbers
27:06
Exclude the End Numbers
27:33
Example
28:28
Interval Notation: Infinity
29:09
Use -∞ or ∞ to Show an Interval Going on Forever in One Direction or the Other
29:14
Always Use Parentheses
29:50
Examples
30:27
Example 1
31:23
Example 2
35:26
Example 3
38:02
Example 4
42:21
Variables, Equations, & Algebra

35m 31s

Intro
0:00
What is a Variable?
0:05
A Variable is a Placeholder for a Number
0:11
Affects the Output of a Function or a Dependent Variable
0:24
Naming Variables
1:51
Useful to Use Symbols
2:21
What is a Constant?
4:14
A Constant is a Fixed, Unchanging Number
4:28
We Might Refer to a Symbol Representing a Number as a Constant
4:51
What is a Coefficient?
5:33
A Coefficient is a Multiplicative Factor on a Variable
5:37
Not All Coefficients are Constants
5:51
Expressions and Equations
6:42
An Expression is a String of Mathematical Symbols That Make Sense Used Together
7:05
An Equation is a Statement That Two Expression Have the Same Value
8:20
The Idea of Algebra
8:51
Equality
8:59
If Two Things Are the Same *Equal), Then We Can Do the Exact Same Operation to Both and the Results Will Be the Same
9:41
Always Do The Exact Same Thing to Both Sides
12:22
Solving Equations
13:23
When You Are Asked to Solve an Equation, You Are Being Asked to Solve for Something
13:33
Look For What Values Makes the Equation True
13:38
Isolate the Variable by Doing Algebra
14:37
Order of Operations
16:02
Why Certain Operations are Grouped
17:01
When You Don't Have to Worry About Order
17:39
Distributive Property
18:15
It Allows Multiplication to Act Over Addition in Parentheses
18:23
We Can Use the Distributive Property in Reverse to Combine Like Terms
19:05
Substitution
20:03
Use Information From One Equation in Another Equation
20:07
Put Your Substitution in Parentheses
20:44
Example 1
23:17
Example 2
25:49
Example 3
28:11
Example 4
30:02
Coordinate Systems

35m 2s

Intro
0:00
Inherent Order in ℝ
0:05
Real Numbers Come with an Inherent Order
0:11
Positive Numbers
0:21
Negative Numbers
0:58
'Less Than' and 'Greater Than'
2:04
Tip To Help You Remember the Signs
2:56
Inequality
4:06
Less Than or Equal and Greater Than or Equal
4:51
One Dimension: The Number Line
5:36
Graphically Represent ℝ on a Number Line
5:43
Note on Infinities
5:57
With the Number Line, We Can Directly See the Order We Put on ℝ
6:35
Ordered Pairs
7:22
Example
7:34
Allows Us to Talk About Two Numbers at the Same Time
9:41
Ordered Pairs of Real Numbers Cannot be Put Into an Order Like we Did with ℝ
10:41
Two Dimensions: The Plane
13:13
We Can Represent Ordered Pairs with the Plane
13:24
Intersection is known as the Origin
14:31
Plotting the Point
14:32
Plane = Coordinate Plane = Cartesian Plane = ℝ²
17:46
The Plane and Quadrants
18:50
Quadrant I
19:04
Quadrant II
19:21
Quadrant III
20:04
Quadrant IV
20:20
Three Dimensions: Space
21:02
Create Ordered Triplets
21:09
Visually Represent This
21:19
Three-Dimension = Space = ℝ³
21:47
Higher Dimensions
22:24
If We Have n Dimensions, We Call It n-Dimensional Space or ℝ to the nth Power
22:31
We Can Represent Places In This n-Dimensional Space As Ordered Groupings of n Numbers
22:41
Hard to Visualize Higher Dimensional Spaces
23:18
Example 1
25:07
Example 2
26:10
Example 3
28:58
Example 4
31:05
Midpoints, Distance, the Pythagorean Theorem, & Slope

48m 43s

Intro
0:00
Introduction
0:07
Midpoint: One Dimension
2:09
Example of Something More Complex
2:31
Use the Idea of a Middle
3:28
Find the Midpoint of Arbitrary Values a and b
4:17
How They're Equivalent
5:05
Official Midpoint Formula
5:46
Midpoint: Two Dimensions
6:19
The Midpoint Must Occur at the Horizontal Middle and the Vertical Middle
6:38
Arbitrary Pair of Points Example
7:25
Distance: One Dimension
9:26
Absolute Value
10:54
Idea of Forcing Positive
11:06
Distance: One Dimension, Formula
11:47
Distance Between Arbitrary a and b
11:48
Absolute Value Helps When the Distance is Negative
12:41
Distance Formula
12:58
The Pythagorean Theorem
13:24
a²+b²=c²
13:50
Distance: Two Dimensions
14:59
Break Into Horizontal and Vertical Parts and then Use the Pythagorean Theorem
15:16
Distance Between Arbitrary Points (x₁,y₁) and (x₂,y₂)
16:21
Slope
19:30
Slope is the Rate of Change
19:41
m = rise over run
21:27
Slope Between Arbitrary Points (x₁,y₁) and (x₂,y₂)
22:31
Interpreting Slope
24:12
Positive Slope and Negative Slope
25:40
m=1, m=0, m=-1
26:48
Example 1
28:25
Example 2
31:42
Example 3
36:40
Example 4
42:48
Word Problems

56m 31s

Intro
0:00
Introduction
0:05
What is a Word Problem?
0:45
Describes Any Problem That Primarily Gets Its Ideas Across With Words Instead of Math Symbols
0:48
Requires Us to Think
1:32
Why Are They So Hard?
2:11
Reason 1: No Simple Formula to Solve Them
2:16
Reason 2: Harder to Teach Word Problems
2:47
You Can Learn How to Do Them!
3:51
Grades
7:57
'But I'm Never Going to Use This In Real Life'
9:46
Solving Word Problems
12:58
First: Understand the Problem
13:37
Second: What Are You Looking For?
14:33
Third: Set Up Relationships
16:21
Fourth: Solve It!
17:48
Summary of Method
19:04
Examples on Things Other Than Math
20:21
Math-Specific Method: What You Need Now
25:30
Understand What the Problem is Talking About
25:37
Set Up and Name Any Variables You Need to Know
25:56
Set Up Equations Connecting Those Variables to the Information in the Problem Statement
26:02
Use the Equations to Solve for an Answer
26:14
Tip
26:58
Draw Pictures
27:22
Breaking Into Pieces
28:28
Try Out Hypothetical Numbers
29:52
Student Logic
31:27
Jump In!
32:40
Example 1
34:03
Example 2
39:15
Example 3
44:22
Example 4
50:24
II. Functions
Idea of a Function

39m 54s

Intro
0:00
Introduction
0:04
What is a Function?
1:06
A Visual Example and Non-Example
1:30
Function Notation
3:47
f(x)
4:05
Express What Sets the Function Acts On
5:45
Metaphors for a Function
6:17
Transformation
6:28
Map
7:17
Machine
8:56
Same Input Always Gives Same Output
10:01
If We Put the Same Input Into a Function, It Will Always Produce the Same Output
10:11
Example of Something That is Not a Function
11:10
A Non-Numerical Example
12:10
The Functions We Will Use
15:05
Unless Told Otherwise, We Will Assume Every Function Takes in Real Numbers and Outputs Real Numbers
15:11
Usually Told the Rule of a Given Function
15:27
How To Use a Function
16:18
Apply the Rule to Whatever Our Input Value Is
16:28
Make Sure to Wrap Your Substitutions in Parentheses
17:09
Functions and Tables
17:36
Table of Values, Sometimes Called a T-Table
17:46
Example
17:56
Domain: What Goes In
18:55
The Domain is the Set of all Inputs That the Function Can Accept
18:56
Example
19:40
Range: What Comes Out
21:27
The Range is the Set of All Possible Outputs a Function Can Assign
21:34
Example
21:49
Another Example Would Be Our Initial Function From Earlier in This Lesson
22:29
Example 1
23:45
Example 2
25:22
Example 3
27:27
Example 4
29:23
Example 5
33:33
Graphs

58m 26s

Intro
0:00
Introduction
0:04
How to Interpret Graphs
1:17
Input / Independent Variable
1:47
Output / Dependent Variable
2:00
Graph as Input ⇒ Output
2:23
One Way to Think of a Graph: See What Happened to Various Inputs
2:25
Example
2:47
Graph as Location of Solution
4:20
A Way to See Solutions
4:36
Example
5:20
Which Way Should We Interpret?
7:13
Easiest to Think In Terms of How Inputs Are Mapped to Outputs
7:20
Sometimes It's Easier to Think In Terms of Solutions
8:39
Pay Attention to Axes
9:50
Axes Tell Where the Graph Is and What Scale It Has
10:09
Often, The Axes Will Be Square
10:14
Example
12:06
Arrows or No Arrows?
16:07
Will Not Use Arrows at the End of Our Graphs
17:13
Graph Stops Because It Hits the Edge of the Graphing Axes, Not Because the Function Stops
17:18
How to Graph
19:47
Plot Points
20:07
Connect with Curves
21:09
If You Connect with Straight Lines
21:44
Graphs of Functions are Smooth
22:21
More Points ⇒ More Accurate
23:38
Vertical Line Test
27:44
If a Vertical Line Could Intersect More Than One Point On a Graph, It Can Not Be the Graph of a Function
28:41
Every Point on a Graph Tells Us Where the x-Value Below is Mapped
30:07
Domain in Graphs
31:37
The Domain is the Set of All Inputs That a Function Can Accept
31:44
Be Aware That Our Function Probably Continues Past the Edge of Our 'Viewing Window'
33:19
Range in Graphs
33:53
Graphing Calculators: Check the Appendix!
36:55
Example 1
38:37
Example 2
45:19
Example 3
50:41
Example 4
53:28
Example 5
55:50
Properties of Functions

48m 49s

Intro
0:00
Introduction
0:05
Increasing Decreasing Constant
0:43
Looking at a Specific Graph
1:15
Increasing Interval
2:39
Constant Function
4:15
Decreasing Interval
5:10
Find Intervals by Looking at the Graph
5:32
Intervals Show x-values; Write in Parentheses
6:39
Maximum and Minimums
8:48
Relative (Local) Max/Min
10:20
Formal Definition of Relative Maximum
12:44
Formal Definition of Relative Minimum
13:05
Max/Min, More Terms
14:18
Definition of Extrema
15:01
Average Rate of Change
16:11
Drawing a Line for the Average Rate
16:48
Using the Slope of the Secant Line
17:36
Slope in Function Notation
18:45
Zeros/Roots/x-intercepts
19:45
What Zeros in a Function Mean
20:25
Even Functions
22:30
Odd Functions
24:36
Even/Odd Functions and Graphs
26:28
Example of an Even Function
27:12
Example of an Odd Function
28:03
Example 1
29:35
Example 2
33:07
Example 3
40:32
Example 4
42:34
Function Petting Zoo

29m 20s

Intro
0:00
Introduction
0:04
Don't Forget that Axes Matter!
1:44
The Constant Function
2:40
The Identity Function
3:44
The Square Function
4:40
The Cube Function
5:44
The Square Root Function
6:51
The Reciprocal Function
8:11
The Absolute Value Function
10:19
The Trigonometric Functions
11:56
f(x)=sin(x)
12:12
f(x)=cos(x)
12:24
Alternate Axes
12:40
The Exponential and Logarithmic Functions
13:35
Exponential Functions
13:44
Logarithmic Functions
14:24
Alternating Axes
15:17
Transformations and Compositions
16:08
Example 1
17:52
Example 2
18:33
Example 3
20:24
Example 4
26:07
Transformation of Functions

48m 35s

Intro
0:00
Introduction
0:04
Vertical Shift
1:12
Graphical Example
1:21
A Further Explanation
2:16
Vertical Stretch/Shrink
3:34
Graph Shrinks
3:46
Graph Stretches
3:51
A Further Explanation
5:07
Horizontal Shift
6:49
Moving the Graph to the Right
7:28
Moving the Graph to the Left
8:12
A Further Explanation
8:19
Understanding Movement on the x-axis
8:38
Horizontal Stretch/Shrink
12:59
Shrinking the Graph
13:40
Stretching the Graph
13:48
A Further Explanation
13:55
Understanding Stretches from the x-axis
14:12
Vertical Flip (aka Mirror)
16:55
Example Graph
17:07
Multiplying the Vertical Component by -1
17:18
Horizontal Flip (aka Mirror)
18:43
Example Graph
19:01
Multiplying the Horizontal Component by -1
19:54
Summary of Transformations
22:11
Stacking Transformations
24:46
Order Matters
25:20
Transformation Example
25:52
Example 1
29:21
Example 2
34:44
Example 3
38:10
Example 4
43:46
Composite Functions

33m 24s

Intro
0:00
Introduction
0:04
Arithmetic Combinations
0:40
Basic Operations
1:20
Definition of the Four Arithmetic Combinations
1:40
Composite Functions
2:53
The Function as a Machine
3:32
Function Compositions as Multiple Machines
3:59
Notation for Composite Functions
4:46
Two Formats
6:02
Another Visual Interpretation
7:17
How to Use Composite Functions
8:21
Example of on Function acting on Another
9:17
Example 1
11:03
Example 2
15:27
Example 3
21:11
Example 4
27:06
Piecewise Functions

51m 42s

Intro
0:00
Introduction
0:04
Analogies to a Piecewise Function
1:16
Different Potatoes
1:41
Factory Production
2:27
Notations for Piecewise Functions
3:39
Notation Examples from Analogies
6:11
Example of a Piecewise (with Table)
7:24
Example of a Non-Numerical Piecewise
11:35
Graphing Piecewise Functions
14:15
Graphing Piecewise Functions, Example
16:26
Continuous Functions
16:57
Statements of Continuity
19:30
Example of Continuous and Non-Continuous Graphs
20:05
Interesting Functions: the Step Function
22:00
Notation for the Step Function
22:40
How the Step Function Works
22:56
Graph of the Step Function
25:30
Example 1
26:22
Example 2
28:49
Example 3
36:50
Example 4
46:11
Inverse Functions

49m 37s

Intro
0:00
Introduction
0:04
Analogy by picture
1:10
How to Denote the inverse
1:40
What Comes out of the Inverse
1:52
Requirement for Reversing
2:02
The Basketball Factory
2:12
The Importance of Information
2:45
One-to-One
4:04
Requirement for Reversibility
4:21
When a Function has an Inverse
4:43
One-to-One
5:13
Not One-to-One
5:50
Not a Function
6:19
Horizontal Line Test
7:01
How to the test Works
7:12
One-to-One
8:12
Not One-to-One
8:45
Definition: Inverse Function
9:12
Formal Definition
9:21
Caution to Students
10:02
Domain and Range
11:12
Finding the Range of the Function Inverse
11:56
Finding the Domain of the Function Inverse
12:11
Inverse of an Inverse
13:09
Its just x!
13:26
Proof
14:03
Graphical Interpretation
17:07
Horizontal Line Test
17:20
Graph of the Inverse
18:04
Swapping Inputs and Outputs to Draw Inverses
19:02
How to Find the Inverse
21:03
What We Are Looking For
21:21
Reversing the Function
21:38
A Method to Find Inverses
22:33
Check Function is One-to-One
23:04
Swap f(x) for y
23:25
Interchange x and y
23:41
Solve for y
24:12
Replace y with the inverse
24:40
Some Comments
25:01
Keeping Step 2 and 3 Straight
25:44
Switching to Inverse
26:12
Checking Inverses
28:52
How to Check an Inverse
29:06
Quick Example of How to Check
29:56
Example 1
31:48
Example 2
34:56
Example 3
39:29
Example 4
46:19
Variation Direct and Inverse

28m 49s

Intro
0:00
Introduction
0:06
Direct Variation
1:14
Same Direction
1:21
Common Example: Groceries
1:56
Different Ways to Say that Two Things Vary Directly
2:28
Basic Equation for Direct Variation
2:55
Inverse Variation
3:40
Opposite Direction
3:50
Common Example: Gravity
4:53
Different Ways to Say that Two Things Vary Indirectly
5:48
Basic Equation for Indirect Variation
6:33
Joint Variation
7:27
Equation for Joint Variation
7:53
Explanation of the Constant
8:48
Combined Variation
9:35
Gas Law as a Combination
9:44
Single Constant
10:33
Example 1
10:49
Example 2
13:34
Example 3
15:39
Example 4
19:48
III. Polynomials
Intro to Polynomials

38m 41s

Intro
0:00
Introduction
0:04
Definition of a Polynomial
1:04
Starting Integer
2:06
Structure of a Polynomial
2:49
The a Constants
3:34
Polynomial Function
5:13
Polynomial Equation
5:23
Polynomials with Different Variables
5:36
Degree
6:23
Informal Definition
6:31
Find the Largest Exponent Variable
6:44
Quick Examples
7:36
Special Names for Polynomials
8:59
Based on the Degree
9:23
Based on the Number of Terms
10:12
Distributive Property (aka 'FOIL')
11:37
Basic Distributive Property
12:21
Distributing Two Binomials
12:55
Longer Parentheses
15:12
Reverse: Factoring
17:26
Long-Term Behavior of Polynomials
17:48
Examples
18:13
Controlling Term--Term with the Largest Exponent
19:33
Positive and Negative Coefficients on the Controlling Term
20:21
Leading Coefficient Test
22:07
Even Degree, Positive Coefficient
22:13
Even Degree, Negative Coefficient
22:39
Odd Degree, Positive Coefficient
23:09
Odd Degree, Negative Coefficient
23:27
Example 1
25:11
Example 2
27:16
Example 3
31:16
Example 4
34:41
Roots (Zeros) of Polynomials

41m 7s

Intro
0:00
Introduction
0:05
Roots in Graphs
1:17
The x-intercepts
1:33
How to Remember What 'Roots' Are
1:50
Naïve Attempts
2:31
Isolating Variables
2:45
Failures of Isolating Variables
3:30
Missing Solutions
4:59
Factoring: How to Find Roots
6:28
How Factoring Works
6:36
Why Factoring Works
7:20
Steps to Finding Polynomial Roots
9:21
Factoring: How to Find Roots CAUTION
10:08
Factoring is Not Easy
11:32
Factoring Quadratics
13:08
Quadratic Trinomials
13:21
Form of Factored Binomials
13:38
Factoring Examples
14:40
Factoring Quadratics, Check Your Work
16:58
Factoring Higher Degree Polynomials
18:19
Factoring a Cubic
18:32
Factoring a Quadratic
19:04
Factoring: Roots Imply Factors
19:54
Where a Root is, A Factor Is
20:01
How to Use Known Roots to Make Factoring Easier
20:35
Not all Polynomials Can be Factored
22:30
Irreducible Polynomials
23:27
Complex Numbers Help
23:55
Max Number of Roots/Factors
24:57
Limit to Number of Roots Equal to the Degree
25:18
Why there is a Limit
25:25
Max Number of Peaks/Valleys
26:39
Shape Information from Degree
26:46
Example Graph
26:54
Max, But Not Required
28:00
Example 1
28:37
Example 2
31:21
Example 3
36:12
Example 4
38:40
Completing the Square and the Quadratic Formula

39m 43s

Intro
0:00
Introduction
0:05
Square Roots and Equations
0:51
Taking the Square Root to Find the Value of x
0:55
Getting the Positive and Negative Answers
1:05
Completing the Square: Motivation
2:04
Polynomials that are Easy to Solve
2:20
Making Complex Polynomials Easy to Solve
3:03
Steps to Completing the Square
4:30
Completing the Square: Method
7:22
Move C over
7:35
Divide by A
7:44
Find r
7:59
Add to Both Sides to Complete the Square
8:49
Solving Quadratics with Ease
9:56
The Quadratic Formula
11:38
Derivation
11:43
Final Form
12:23
Follow Format to Use Formula
13:38
How Many Roots?
14:53
The Discriminant
15:47
What the Discriminant Tells Us: How Many Roots
15:58
How the Discriminant Works
16:30
Example 1: Complete the Square
18:24
Example 2: Solve the Quadratic
22:00
Example 3: Solve for Zeroes
25:28
Example 4: Using the Quadratic Formula
30:52
Properties of Quadratic Functions

45m 34s

Intro
0:00
Introduction
0:05
Parabolas
0:35
Examples of Different Parabolas
1:06
Axis of Symmetry and Vertex
1:28
Drawing an Axis of Symmetry
1:51
Placing the Vertex
2:28
Looking at the Axis of Symmetry and Vertex for other Parabolas
3:09
Transformations
4:18
Reviewing Transformation Rules
6:28
Note the Different Horizontal Shift Form
7:45
An Alternate Form to Quadratics
8:54
The Constants: k, h, a
9:05
Transformations Formed
10:01
Analyzing Different Parabolas
10:10
Switching Forms by Completing the Square
11:43
Vertex of a Parabola
16:30
Vertex at (h, k)
16:47
Vertex in Terms of a, b, and c Coefficients
17:28
Minimum/Maximum at Vertex
18:19
When a is Positive
18:25
When a is Negative
18:52
Axis of Symmetry
19:54
Incredibly Minor Note on Grammar
20:52
Example 1
21:48
Example 2
26:35
Example 3
28:55
Example 4
31:40
Intermediate Value Theorem and Polynomial Division

46m 8s

Intro
0:00
Introduction
0:05
Reminder: Roots Imply Factors
1:32
The Intermediate Value Theorem
3:41
The Basis: U between a and b
4:11
U is on the Function
4:52
Intermediate Value Theorem, Proof Sketch
5:51
If Not True, the Graph Would Have to Jump
5:58
But Graph is Defined as Continuous
6:43
Finding Roots with the Intermediate Value Theorem
7:01
Picking a and b to be of Different Signs
7:10
Must Be at Least One Root
7:46
Dividing a Polynomial
8:16
Using Roots and Division to Factor
8:38
Long Division Refresher
9:08
The Division Algorithm
12:18
How It Works to Divide Polynomials
12:37
The Parts of the Equation
13:24
Rewriting the Equation
14:47
Polynomial Long Division
16:20
Polynomial Long Division In Action
16:29
One Step at a Time
20:51
Synthetic Division
22:46
Setup
23:11
Synthetic Division, Example
24:44
Which Method Should We Use
26:39
Advantages of Synthetic Method
26:49
Advantages of Long Division
27:13
Example 1
29:24
Example 2
31:27
Example 3
36:22
Example 4
40:55
Complex Numbers

45m 36s

Intro
0:00
Introduction
0:04
A Wacky Idea
1:02
The Definition of the Imaginary Number
1:22
How it Helps Solve Equations
2:20
Square Roots and Imaginary Numbers
3:15
Complex Numbers
5:00
Real Part and Imaginary Part
5:20
When Two Complex Numbers are Equal
6:10
Addition and Subtraction
6:40
Deal with Real and Imaginary Parts Separately
7:36
Two Quick Examples
7:54
Multiplication
9:07
FOIL Expansion
9:14
Note What Happens to the Square of the Imaginary Number
9:41
Two Quick Examples
10:22
Division
11:27
Complex Conjugates
13:37
Getting Rid of i
14:08
How to Denote the Conjugate
14:48
Division through Complex Conjugates
16:11
Multiply by the Conjugate of the Denominator
16:28
Example
17:46
Factoring So-Called 'Irreducible' Quadratics
19:24
Revisiting the Quadratic Formula
20:12
Conjugate Pairs
20:37
But Are the Complex Numbers 'Real'?
21:27
What Makes a Number Legitimate
25:38
Where Complex Numbers are Used
27:20
Still, We Won't See Much of C
29:05
Example 1
30:30
Example 2
33:15
Example 3
38:12
Example 4
42:07
Fundamental Theorem of Algebra

19m 9s

Intro
0:00
Introduction
0:05
Idea: Hidden Roots
1:16
Roots in Complex Form
1:42
All Polynomials Have Roots
2:08
Fundamental Theorem of Algebra
2:21
Where Are All the Imaginary Roots, Then?
3:17
All Roots are Complex
3:45
Real Numbers are a Subset of Complex Numbers
3:59
The n Roots Theorem
5:01
For Any Polynomial, Its Degree is Equal to the Number of Roots
5:11
Equivalent Statement
5:24
Comments: Multiplicity
6:29
Non-Distinct Roots
6:59
Denoting Multiplicity
7:20
Comments: Complex Numbers Necessary
7:41
Comments: Complex Coefficients Allowed
8:55
Comments: Existence Theorem
9:59
Proof Sketch of n Roots Theorem
10:45
First Root
11:36
Second Root
13:23
Continuation to Find all Roots
16:00
IV. Rational Functions
Rational Functions and Vertical Asymptotes

33m 22s

Intro
0:00
Introduction
0:05
Definition of a Rational Function
1:20
Examples of Rational Functions
2:30
Why They are Called 'Rational'
2:47
Domain of a Rational Function
3:15
Undefined at Denominator Zeros
3:25
Otherwise all Reals
4:16
Investigating a Fundamental Function
4:50
The Domain of the Function
5:04
What Occurs at the Zeroes of the Denominator
5:20
Idea of a Vertical Asymptote
6:23
What's Going On?
6:58
Approaching x=0 from the left
7:32
Approaching x=0 from the right
8:34
Dividing by Very Small Numbers Results in Very Large Numbers
9:31
Definition of a Vertical Asymptote
10:05
Vertical Asymptotes and Graphs
11:15
Drawing Asymptotes by Using a Dashed Line
11:27
The Graph Can Never Touch Its Undefined Point
12:00
Not All Zeros Give Asymptotes
13:02
Special Cases: When Numerator and Denominator Go to Zero at the Same Time
14:58
Cancel out Common Factors
15:49
How to Find Vertical Asymptotes
16:10
Figure out What Values Are Not in the Domain of x
16:24
Determine if the Numerator and Denominator Share Common Factors and Cancel
16:45
Find Denominator Roots
17:33
Note if Asymptote Approaches Negative or Positive Infinity
18:06
Example 1
18:57
Example 2
21:26
Example 3
23:04
Example 4
30:01
Horizontal Asymptotes

34m 16s

Intro
0:00
Introduction
0:05
Investigating a Fundamental Function
0:53
What Happens as x Grows Large
1:00
Different View
1:12
Idea of a Horizontal Asymptote
1:36
What's Going On?
2:24
What Happens as x Grows to a Large Negative Number
2:49
What Happens as x Grows to a Large Number
3:30
Dividing by Very Large Numbers Results in Very Small Numbers
3:52
Example Function
4:41
Definition of a Vertical Asymptote
8:09
Expanding the Idea
9:03
What's Going On?
9:48
What Happens to the Function in the Long Run?
9:51
Rewriting the Function
10:13
Definition of a Slant Asymptote
12:09
Symbolical Definition
12:30
Informal Definition
12:45
Beyond Slant Asymptotes
13:03
Not Going Beyond Slant Asymptotes
14:39
Horizontal/Slant Asymptotes and Graphs
15:43
How to Find Horizontal and Slant Asymptotes
16:52
How to Find Horizontal Asymptotes
17:12
Expand the Given Polynomials
17:18
Compare the Degrees of the Numerator and Denominator
17:40
How to Find Slant Asymptotes
20:05
Slant Asymptotes Exist When n+m=1
20:08
Use Polynomial Division
20:24
Example 1
24:32
Example 2
25:53
Example 3
26:55
Example 4
29:22
Graphing Asymptotes in a Nutshell

49m 7s

Intro
0:00
Introduction
0:05
A Process for Graphing
1:22
1. Factor Numerator and Denominator
1:50
2. Find Domain
2:53
3. Simplifying the Function
3:59
4. Find Vertical Asymptotes
4:59
5. Find Horizontal/Slant Asymptotes
5:24
6. Find Intercepts
7:35
7. Draw Graph (Find Points as Necessary)
9:21
Draw Graph Example
11:21
Vertical Asymptote
11:41
Horizontal Asymptote
11:50
Other Graphing
12:16
Test Intervals
15:08
Example 1
17:57
Example 2
23:01
Example 3
29:02
Example 4
33:37
Partial Fractions

44m 56s

Intro
0:00
Introduction: Idea
0:04
Introduction: Prerequisites and Uses
1:57
Proper vs. Improper Polynomial Fractions
3:11
Possible Things in the Denominator
4:38
Linear Factors
6:16
Example of Linear Factors
7:03
Multiple Linear Factors
7:48
Irreducible Quadratic Factors
8:25
Example of Quadratic Factors
9:26
Multiple Quadratic Factors
9:49
Mixing Factor Types
10:28
Figuring Out the Numerator
11:10
How to Solve for the Constants
11:30
Quick Example
11:40
Example 1
14:29
Example 2
18:35
Example 3
20:33
Example 4
28:51
V. Exponential & Logarithmic Functions
Understanding Exponents

35m 17s

Intro
0:00
Introduction
0:05
Fundamental Idea
1:46
Expanding the Idea
2:28
Multiplication of the Same Base
2:40
Exponents acting on Exponents
3:45
Different Bases with the Same Exponent
4:31
To the Zero
5:35
To the First
5:45
Fundamental Rule with the Zero Power
6:35
To the Negative
7:45
Any Number to a Negative Power
8:14
A Fraction to a Negative Power
9:58
Division with Exponential Terms
10:41
To the Fraction
11:33
Square Root
11:58
Any Root
12:59
Summary of Rules
14:38
To the Irrational
17:21
Example 1
20:34
Example 2
23:42
Example 3
27:44
Example 4
31:44
Example 5
33:15
Exponential Functions

47m 4s

Intro
0:00
Introduction
0:05
Definition of an Exponential Function
0:48
Definition of the Base
1:02
Restrictions on the Base
1:16
Computing Exponential Functions
2:29
Harder Computations
3:10
When to Use a Calculator
3:21
Graphing Exponential Functions: a>1
6:02
Three Examples
6:13
What to Notice on the Graph
7:44
A Story
8:27
Story Diagram
9:15
Increasing Exponentials
11:29
Story Morals
14:40
Application: Compound Interest
15:15
Compounding Year after Year
16:01
Function for Compounding Interest
16:51
A Special Number: e
20:55
Expression for e
21:28
Where e stabilizes
21:55
Application: Continuously Compounded Interest
24:07
Equation for Continuous Compounding
24:22
Exponential Decay 0<a<1
25:50
Three Examples
26:11
Why they 'lose' value
26:54
Example 1
27:47
Example 2
33:11
Example 3
36:34
Example 4
41:28
Introduction to Logarithms

40m 31s

Intro
0:00
Introduction
0:04
Definition of a Logarithm, Base 2
0:51
Log 2 Defined
0:55
Examples
2:28
Definition of a Logarithm, General
3:23
Examples of Logarithms
5:15
Problems with Unusual Bases
7:38
Shorthand Notation: ln and log
9:44
base e as ln
10:01
base 10 as log
10:34
Calculating Logarithms
11:01
using a calculator
11:34
issues with other bases
11:58
Graphs of Logarithms
13:21
Three Examples
13:29
Slow Growth
15:19
Logarithms as Inverse of Exponentiation
16:02
Using Base 2
16:05
General Case
17:10
Looking More Closely at Logarithm Graphs
19:16
The Domain of Logarithms
20:41
Thinking about Logs like Inverses
21:08
The Alternate
24:00
Example 1
25:59
Example 2
30:03
Example 3
32:49
Example 4
37:34
Properties of Logarithms

42m 33s

Intro
0:00
Introduction
0:04
Basic Properties
1:12
Inverse--log(exp)
1:43
A Key Idea
2:44
What We Get through Exponentiation
3:18
B Always Exists
4:50
Inverse--exp(log)
5:53
Logarithm of a Power
7:44
Logarithm of a Product
10:07
Logarithm of a Quotient
13:48
Caution! There Is No Rule for loga(M+N)
16:12
Summary of Properties
17:42
Change of Base--Motivation
20:17
No Calculator Button
20:59
A Specific Example
21:45
Simplifying
23:45
Change of Base--Formula
24:14
Example 1
25:47
Example 2
29:08
Example 3
31:14
Example 4
34:13
Solving Exponential and Logarithmic Equations

34m 10s

Intro
0:00
Introduction
0:05
One to One Property
1:09
Exponential
1:26
Logarithmic
1:44
Specific Considerations
2:02
One-to-One Property
3:30
Solving by One-to-One
4:11
Inverse Property
6:09
Solving by Inverses
7:25
Dealing with Equations
7:50
Example of Taking an Exponent or Logarithm of an Equation
9:07
A Useful Property
11:57
Bring Down Exponents
12:01
Try to Simplify
13:20
Extraneous Solutions
13:45
Example 1
16:37
Example 2
19:39
Example 3
21:37
Example 4
26:45
Example 5
29:37
Application of Exponential and Logarithmic Functions

48m 46s

Intro
0:00
Introduction
0:06
Applications of Exponential Functions
1:07
A Secret!
2:17
Natural Exponential Growth Model
3:07
Figure out r
3:34
A Secret!--Why Does It Work?
4:44
e to the r Morphs
4:57
Example
5:06
Applications of Logarithmic Functions
8:32
Examples
8:43
What Logarithms are Useful For
9:53
Example 1
11:29
Example 2
15:30
Example 3
26:22
Example 4
32:05
Example 5
39:19
VI. Trigonometric Functions
Angles

39m 5s

Intro
0:00
Degrees
0:22
Circle is 360 Degrees
0:48
Splitting a Circle
1:13
Radians
2:08
Circle is 2 Pi Radians
2:31
One Radian
2:52
Half-Circle and Right Angle
4:00
Converting Between Degrees and Radians
6:24
Formulas for Degrees and Radians
6:52
Coterminal, Complementary, Supplementary Angles
7:23
Coterminal Angles
7:30
Complementary Angles
9:40
Supplementary Angles
10:08
Example 1: Dividing a Circle
10:38
Example 2: Converting Between Degrees and Radians
11:56
Example 3: Quadrants and Coterminal Angles
14:18
Extra Example 1: Common Angle Conversions
-1
Extra Example 2: Quadrants and Coterminal Angles
-2
Sine and Cosine Functions

43m 16s

Intro
0:00
Sine and Cosine
0:15
Unit Circle
0:22
Coordinates on Unit Circle
1:03
Right Triangles
1:52
Adjacent, Opposite, Hypotenuse
2:25
Master Right Triangle Formula: SOHCAHTOA
2:48
Odd Functions, Even Functions
4:40
Example: Odd Function
4:56
Example: Even Function
7:30
Example 1: Sine and Cosine
10:27
Example 2: Graphing Sine and Cosine Functions
14:39
Example 3: Right Triangle
21:40
Example 4: Odd, Even, or Neither
26:01
Extra Example 1: Right Triangle
-1
Extra Example 2: Graphing Sine and Cosine Functions
-2
Sine and Cosine Values of Special Angles

33m 5s

Intro
0:00
45-45-90 Triangle and 30-60-90 Triangle
0:08
45-45-90 Triangle
0:21
30-60-90 Triangle
2:06
Mnemonic: All Students Take Calculus (ASTC)
5:21
Using the Unit Circle
5:59
New Angles
6:21
Other Quadrants
9:43
Mnemonic: All Students Take Calculus
10:13
Example 1: Convert, Quadrant, Sine/Cosine
13:11
Example 2: Convert, Quadrant, Sine/Cosine
16:48
Example 3: All Angles and Quadrants
20:21
Extra Example 1: Convert, Quadrant, Sine/Cosine
-1
Extra Example 2: All Angles and Quadrants
-2
Modified Sine Waves: Asin(Bx+C)+D and Acos(Bx+C)+D

52m 3s

Intro
0:00
Amplitude and Period of a Sine Wave
0:38
Sine Wave Graph
0:58
Amplitude: Distance from Middle to Peak
1:18
Peak: Distance from Peak to Peak
2:41
Phase Shift and Vertical Shift
4:13
Phase Shift: Distance Shifted Horizontally
4:16
Vertical Shift: Distance Shifted Vertically
6:48
Example 1: Amplitude/Period/Phase and Vertical Shift
8:04
Example 2: Amplitude/Period/Phase and Vertical Shift
17:39
Example 3: Find Sine Wave Given Attributes
25:23
Extra Example 1: Amplitude/Period/Phase and Vertical Shift
-1
Extra Example 2: Find Cosine Wave Given Attributes
-2
Tangent and Cotangent Functions

36m 4s

Intro
0:00
Tangent and Cotangent Definitions
0:21
Tangent Definition
0:25
Cotangent Definition
0:47
Master Formula: SOHCAHTOA
1:01
Mnemonic
1:16
Tangent and Cotangent Values
2:29
Remember Common Values of Sine and Cosine
2:46
90 Degrees Undefined
4:36
Slope and Menmonic: ASTC
5:47
Uses of Tangent
5:54
Example: Tangent of Angle is Slope
6:09
Sign of Tangent in Quadrants
7:49
Example 1: Graph Tangent and Cotangent Functions
10:42
Example 2: Tangent and Cotangent of Angles
16:09
Example 3: Odd, Even, or Neither
18:56
Extra Example 1: Tangent and Cotangent of Angles
-1
Extra Example 2: Tangent and Cotangent of Angles
-2
Secant and Cosecant Functions

27m 18s

Intro
0:00
Secant and Cosecant Definitions
0:17
Secant Definition
0:18
Cosecant Definition
0:33
Example 1: Graph Secant Function
0:48
Example 2: Values of Secant and Cosecant
6:49
Example 3: Odd, Even, or Neither
12:49
Extra Example 1: Graph of Cosecant Function
-1
Extra Example 2: Values of Secant and Cosecant
-2
Inverse Trigonometric Functions

32m 58s

Intro
0:00
Arcsine Function
0:24
Restrictions between -1 and 1
0:43
Arcsine Notation
1:26
Arccosine Function
3:07
Restrictions between -1 and 1
3:36
Cosine Notation
3:53
Arctangent Function
4:30
Between -Pi/2 and Pi/2
4:44
Tangent Notation
5:02
Example 1: Domain/Range/Graph of Arcsine
5:45
Example 2: Arcsin/Arccos/Arctan Values
10:46
Example 3: Domain/Range/Graph of Arctangent
17:14
Extra Example 1: Domain/Range/Graph of Arccosine
-1
Extra Example 2: Arcsin/Arccos/Arctan Values
-2
Computations of Inverse Trigonometric Functions

31m 8s

Intro
0:00
Inverse Trigonometric Function Domains and Ranges
0:31
Arcsine
0:41
Arccosine
1:14
Arctangent
1:41
Example 1: Arcsines of Common Values
2:44
Example 2: Odd, Even, or Neither
5:57
Example 3: Arccosines of Common Values
12:24
Extra Example 1: Arctangents of Common Values
-1
Extra Example 2: Arcsin/Arccos/Arctan Values
-2
VII. Trigonometric Identities
Pythagorean Identity

19m 11s

Intro
0:00
Pythagorean Identity
0:17
Pythagorean Triangle
0:27
Pythagorean Identity
0:45
Example 1: Use Pythagorean Theorem to Prove Pythagorean Identity
1:14
Example 2: Find Angle Given Cosine and Quadrant
4:18
Example 3: Verify Trigonometric Identity
8:00
Extra Example 1: Use Pythagorean Identity to Prove Pythagorean Theorem
-1
Extra Example 2: Find Angle Given Cosine and Quadrant
-2
Identity Tan(squared)x+1=Sec(squared)x

23m 16s

Intro
0:00
Main Formulas
0:19
Companion to Pythagorean Identity
0:27
For Cotangents and Cosecants
0:52
How to Remember
0:58
Example 1: Prove the Identity
1:40
Example 2: Given Tan Find Sec
3:42
Example 3: Prove the Identity
7:45
Extra Example 1: Prove the Identity
-1
Extra Example 2: Given Sec Find Tan
-2
Addition and Subtraction Formulas

52m 52s

Intro
0:00
Addition and Subtraction Formulas
0:09
How to Remember
0:48
Cofunction Identities
1:31
How to Remember Graphically
1:44
Where to Use Cofunction Identities
2:52
Example 1: Derive the Formula for cos(A-B)
3:08
Example 2: Use Addition and Subtraction Formulas
16:03
Example 3: Use Addition and Subtraction Formulas to Prove Identity
25:11
Extra Example 1: Use cos(A-B) and Cofunction Identities
-1
Extra Example 2: Convert to Radians and use Formulas
-2
Double Angle Formulas

29m 5s

Intro
0:00
Main Formula
0:07
How to Remember from Addition Formula
0:18
Two Other Forms
1:35
Example 1: Find Sine and Cosine of Angle using Double Angle
3:16
Example 2: Prove Trigonometric Identity using Double Angle
9:37
Example 3: Use Addition and Subtraction Formulas
12:38
Extra Example 1: Find Sine and Cosine of Angle using Double Angle
-1
Extra Example 2: Prove Trigonometric Identity using Double Angle
-2
Half-Angle Formulas

43m 55s

Intro
0:00
Main Formulas
0:09
Confusing Part
0:34
Example 1: Find Sine and Cosine of Angle using Half-Angle
0:54
Example 2: Prove Trigonometric Identity using Half-Angle
11:51
Example 3: Prove the Half-Angle Formula for Tangents
18:39
Extra Example 1: Find Sine and Cosine of Angle using Half-Angle
-1
Extra Example 2: Prove Trigonometric Identity using Half-Angle
-2
VIII. Applications of Trigonometry
Trigonometry in Right Angles

25m 43s

Intro
0:00
Master Formula for Right Angles
0:11
SOHCAHTOA
0:15
Only for Right Triangles
1:26
Example 1: Find All Angles in a Triangle
2:19
Example 2: Find Lengths of All Sides of Triangle
7:39
Example 3: Find All Angles in a Triangle
11:00
Extra Example 1: Find All Angles in a Triangle
-1
Extra Example 2: Find Lengths of All Sides of Triangle
-2
Law of Sines

56m 40s

Intro
0:00
Law of Sines Formula
0:18
SOHCAHTOA
0:27
Any Triangle
0:59
Graphical Representation
1:25
Solving Triangle Completely
2:37
When to Use Law of Sines
2:55
ASA, SAA, SSA, AAA
2:59
SAS, SSS for Law of Cosines
7:11
Example 1: How Many Triangles Satisfy Conditions, Solve Completely
8:44
Example 2: How Many Triangles Satisfy Conditions, Solve Completely
15:30
Example 3: How Many Triangles Satisfy Conditions, Solve Completely
28:32
Extra Example 1: How Many Triangles Satisfy Conditions, Solve Completely
-1
Extra Example 2: How Many Triangles Satisfy Conditions, Solve Completely
-2
Law of Cosines

49m 5s

Intro
0:00
Law of Cosines Formula
0:23
Graphical Representation
0:34
Relates Sides to Angles
1:00
Any Triangle
1:20
Generalization of Pythagorean Theorem
1:32
When to Use Law of Cosines
2:26
SAS, SSS
2:30
Heron's Formula
4:49
Semiperimeter S
5:11
Example 1: How Many Triangles Satisfy Conditions, Solve Completely
5:53
Example 2: How Many Triangles Satisfy Conditions, Solve Completely
15:19
Example 3: Find Area of a Triangle Given All Side Lengths
26:33
Extra Example 1: How Many Triangles Satisfy Conditions, Solve Completely
-1
Extra Example 2: Length of Third Side and Area of Triangle
-2
Finding the Area of a Triangle

27m 37s

Intro
0:00
Master Right Triangle Formula and Law of Cosines
0:19
SOHCAHTOA
0:27
Law of Cosines
1:23
Heron's Formula
2:22
Semiperimeter S
2:37
Example 1: Area of Triangle with Two Sides and One Angle
3:12
Example 2: Area of Triangle with Three Sides
6:11
Example 3: Area of Triangle with Three Sides, No Heron's Formula
8:50
Extra Example 1: Area of Triangle with Two Sides and One Angle
-1
Extra Example 2: Area of Triangle with Two Sides and One Angle
-2
Word Problems and Applications of Trigonometry

34m 25s

Intro
0:00
Formulas to Remember
0:11
SOHCAHTOA
0:15
Law of Sines
0:55
Law of Cosines
1:48
Heron's Formula
2:46
Example 1: Telephone Pole Height
4:01
Example 2: Bridge Length
7:48
Example 3: Area of Triangular Field
14:20
Extra Example 1: Kite Height
-1
Extra Example 2: Roads to a Town
-2
IX. Systems of Equations and Inequalities
Systems of Linear Equations

55m 40s

Intro
0:00
Introduction
0:04
Graphs as Location of 'True'
1:49
All Locations that Make the Function True
2:25
Understand the Relationship Between Solutions and the Graph
3:43
Systems as Graphs
4:07
Equations as Lines
4:20
Intersection Point
5:19
Three Possibilities for Solutions
6:17
Independent
6:24
Inconsistent
6:36
Dependent
7:06
Solving by Substitution
8:37
Solve for One Variable
9:07
Substitute into the Second Equation
9:34
Solve for Both Variables
10:12
What If a System is Inconsistent or Dependent?
11:08
No Solutions
11:25
Infinite Solutions
12:30
Solving by Elimination
13:56
Example
14:22
Determining the Number of Solutions
16:30
Why Elimination Makes Sense
17:25
Solving by Graphing Calculator
19:59
Systems with More than Two Variables
23:22
Example 1
25:49
Example 2
30:22
Example 3
34:11
Example 4
38:55
Example 5
46:01
(Non-) Example 6
53:37
Systems of Linear Inequalities

1h 13s

Intro
0:00
Introduction
0:04
Inequality Refresher-Solutions
0:46
Equation Solutions vs. Inequality Solutions
1:02
Essentially a Wide Variety of Answers
1:35
Refresher--Negative Multiplication Flips
1:43
Refresher--Negative Flips: Why?
3:19
Multiplication by a Negative
3:43
The Relationship Flips
3:55
Refresher--Stick to Basic Operations
4:34
Linear Equations in Two Variables
6:50
Graphing Linear Inequalities
8:28
Why It Includes a Whole Section
8:43
How to Show The Difference Between Strict and Not Strict Inequalities
10:08
Dashed Line--Not Solutions
11:10
Solid Line--Are Solutions
11:24
Test Points for Shading
11:42
Example of Using a Point
12:41
Drawing Shading from the Point
13:14
Graphing a System
14:53
Set of Solutions is the Overlap
15:17
Example
15:22
Solutions are Best Found Through Graphing
18:05
Linear Programming-Idea
19:52
Use a Linear Objective Function
20:15
Variables in Objective Function have Constraints
21:24
Linear Programming-Method
22:09
Rearrange Equations
22:21
Graph
22:49
Critical Solution is at the Vertex of the Overlap
23:40
Try Each Vertice
24:35
Example 1
24:58
Example 2
28:57
Example 3
33:48
Example 4
43:10
Nonlinear Systems

41m 1s

Intro
0:00
Introduction
0:06
Substitution
1:12
Example
1:22
Elimination
3:46
Example
3:56
Elimination is Less Useful for Nonlinear Systems
4:56
Graphing
5:56
Using a Graphing Calculator
6:44
Number of Solutions
8:44
Systems of Nonlinear Inequalities
10:02
Graph Each Inequality
10:06
Dashed and/or Solid
10:18
Shade Appropriately
11:14
Example 1
13:24
Example 2
15:50
Example 3
22:02
Example 4
29:06
Example 4, cont.
33:40
X. Vectors and Matrices
Vectors

1h 9m 31s

Intro
0:00
Introduction
0:10
Magnitude of the Force
0:22
Direction of the Force
0:48
Vector
0:52
Idea of a Vector
1:30
How Vectors are Denoted
2:00
Component Form
3:20
Angle Brackets and Parentheses
3:50
Magnitude/Length
4:26
Denoting the Magnitude of a Vector
5:16
Direction/Angle
7:52
Always Draw a Picture
8:50
Component Form from Magnitude & Angle
10:10
Scaling by Scalars
14:06
Unit Vectors
16:26
Combining Vectors - Algebraically
18:10
Combining Vectors - Geometrically
19:54
Resultant Vector
20:46
Alternate Component Form: i, j
21:16
The Zero Vector
23:18
Properties of Vectors
24:20
No Multiplication (Between Vectors)
28:30
Dot Product
29:40
Motion in a Medium
30:10
Fish in an Aquarium Example
31:38
More Than Two Dimensions
33:12
More Than Two Dimensions - Magnitude
34:18
Example 1
35:26
Example 2
38:10
Example 3
45:48
Example 4
50:40
Example 4, cont.
56:07
Example 5
1:01:32
Dot Product & Cross Product

35m 20s

Intro
0:00
Introduction
0:08
Dot Product - Definition
0:42
Dot Product Results in a Scalar, Not a Vector
2:10
Example in Two Dimensions
2:34
Angle and the Dot Product
2:58
The Dot Product of Two Vectors is Deeply Related to the Angle Between the Two Vectors
2:59
Proof of Dot Product Formula
4:14
Won't Directly Help Us Better Understand Vectors
4:18
Dot Product - Geometric Interpretation
4:58
We Can Interpret the Dot Product as a Measure of How Long and How Parallel Two Vectors Are
7:26
Dot Product - Perpendicular Vectors
8:24
If the Dot Product of Two Vectors is 0, We Know They are Perpendicular to Each Other
8:54
Cross Product - Definition
11:08
Cross Product Only Works in Three Dimensions
11:09
Cross Product - A Mnemonic
12:16
The Determinant of a 3 x 3 Matrix and Standard Unit Vectors
12:17
Cross Product - Geometric Interpretations
14:30
The Right-Hand Rule
15:17
Cross Product - Geometric Interpretations Cont.
17:00
Example 1
18:40
Example 2
22:50
Example 3
24:04
Example 4
26:20
Bonus Round
29:18
Proof: Dot Product Formula
29:24
Proof: Dot Product Formula, cont.
30:38
Matrices

54m 7s

Intro
0:00
Introduction
0:08
Definition of a Matrix
3:02
Size or Dimension
3:58
Square Matrix
4:42
Denoted by Capital Letters
4:56
When are Two Matrices Equal?
5:04
Examples of Matrices
6:44
Rows x Columns
6:46
Talking About Specific Entries
7:48
We Use Capitals to Denote a Matrix and Lower Case to Denotes Its Entries
8:32
Using Entries to Talk About Matrices
10:08
Scalar Multiplication
11:26
Scalar = Real Number
11:34
Example
12:36
Matrix Addition
13:08
Example
14:22
Matrix Multiplication
15:00
Example
18:52
Matrix Multiplication, cont.
19:58
Matrix Multiplication and Order (Size)
25:26
Make Sure Their Orders are Compatible
25:27
Matrix Multiplication is NOT Commutative
28:20
Example
30:08
Special Matrices - Zero Matrix (0)
32:48
Zero Matrix Has 0 for All of its Entries
32:49
Special Matrices - Identity Matrix (I)
34:14
Identity Matrix is a Square Matrix That Has 1 for All Its Entries on the Main Diagonal and 0 for All Other Entries
34:15
Example 1
36:16
Example 2
40:00
Example 3
44:54
Example 4
50:08
Determinants & Inverses of Matrices

47m 12s

Intro
0:00
Introduction
0:06
Not All Matrices Are Invertible
1:30
What Must a Matrix Have to Be Invertible?
2:08
Determinant
2:32
The Determinant is a Real Number Associated With a Square Matrix
2:38
If the Determinant of a Matrix is Nonzero, the Matrix is Invertible
3:40
Determinant of a 2 x 2 Matrix
4:34
Think in Terms of Diagonals
5:12
Minors and Cofactors - Minors
6:24
Example
6:46
Minors and Cofactors - Cofactors
8:00
Cofactor is Closely Based on the Minor
8:01
Alternating Sign Pattern
9:04
Determinant of Larger Matrices
10:56
Example
13:00
Alternative Method for 3x3 Matrices
16:46
Not Recommended
16:48
Inverse of a 2 x 2 Matrix
19:02
Inverse of Larger Matrices
20:00
Using Inverse Matrices
21:06
When Multiplied Together, They Create the Identity Matrix
21:24
Example 1
23:45
Example 2
27:21
Example 3
32:49
Example 4
36:27
Finding the Inverse of Larger Matrices
41:59
General Inverse Method - Step 1
43:25
General Inverse Method - Step 2
43:27
General Inverse Method - Step 2, cont.
43:27
General Inverse Method - Step 3
45:15
Using Matrices to Solve Systems of Linear Equations

58m 34s

Intro
0:00
Introduction
0:12
Augmented Matrix
1:44
We Can Represent the Entire Linear System With an Augmented Matrix
1:50
Row Operations
3:22
Interchange the Locations of Two Rows
3:50
Multiply (or Divide) a Row by a Nonzero Number
3:58
Add (or Subtract) a Multiple of One Row to Another
4:12
Row Operations - Keep Notes!
5:50
Suggested Symbols
7:08
Gauss-Jordan Elimination - Idea
8:04
Gauss-Jordan Elimination - Idea, cont.
9:16
Reduced Row-Echelon Form
9:18
Gauss-Jordan Elimination - Method
11:36
Begin by Writing the System As An Augmented Matrix
11:38
Gauss-Jordan Elimination - Method, cont.
13:48
Cramer's Rule - 2 x 2 Matrices
17:08
Cramer's Rule - n x n Matrices
19:24
Solving with Inverse Matrices
21:10
Solving Inverse Matrices, cont.
25:28
The Mighty (Graphing) Calculator
26:38
Example 1
29:56
Example 2
33:56
Example 3
37:00
Example 3, cont.
45:04
Example 4
51:28
XI. Alternate Ways to Graph
Parametric Equations

53m 33s

Intro
0:00
Introduction
0:06
Definition
1:10
Plane Curve
1:24
The Key Idea
2:00
Graphing with Parametric Equations
2:52
Same Graph, Different Equations
5:04
How Is That Possible?
5:36
Same Graph, Different Equations, cont.
5:42
Here's Another to Consider
7:56
Same Plane Curve, But Still Different
8:10
A Metaphor for Parametric Equations
9:36
Think of Parametric Equations As a Way to Describe the Motion of An Object
9:38
Graph Shows Where It Went, But Not Speed
10:32
Eliminating Parameters
12:14
Rectangular Equation
12:16
Caution
13:52
Creating Parametric Equations
14:30
Interesting Graphs
16:38
Graphing Calculators, Yay!
19:18
Example 1
22:36
Example 2
28:26
Example 3
37:36
Example 4
41:00
Projectile Motion
44:26
Example 5
47:00
Polar Coordinates

48m 7s

Intro
0:00
Introduction
0:04
Polar Coordinates Give Us a Way To Describe the Location of a Point
0:26
Polar Equations and Functions
0:50
Plotting Points with Polar Coordinates
1:06
The Distance of the Point from the Origin
1:09
The Angle of the Point
1:33
Give Points as the Ordered Pair (r,θ)
2:03
Visualizing Plotting in Polar Coordinates
2:32
First Way We Can Plot
2:39
Second Way We Can Plot
2:50
First, We'll Look at Visualizing r, Then θ
3:09
Rotate the Length Counter-Clockwise by θ
3:38
Alternatively, We Can Visualize θ, Then r
4:06
'Polar Graph Paper'
6:17
Horizontal and Vertical Tick Marks Are Not Useful for Polar
6:42
Use Concentric Circles to Helps Up See Distance From the Pole
7:08
Can Use Arc Sectors to See Angles
7:57
Multiple Ways to Name a Point
9:17
Examples
9:30
For Any Angle θ, We Can Make an Equivalent Angle
10:44
Negative Values for r
11:58
If r Is Negative, We Go In The Direction Opposite the One That The Angle θ Points Out
12:22
Another Way to Name the Same Point: Add π to θ and Make r Negative
13:44
Converting Between Rectangular and Polar
14:37
Rectangular Way to Name
14:43
Polar Way to Name
14:52
The Rectangular System Must Have a Right Angle Because It's Based on a Rectangle
15:08
Connect Both Systems Through Basic Trigonometry
15:38
Equation to Convert From Polar to Rectangular Coordinate Systems
16:55
Equation to Convert From Rectangular to Polar Coordinate Systems
17:13
Converting to Rectangular is Easy
17:20
Converting to Polar is a Bit Trickier
17:21
Draw Pictures
18:55
Example 1
19:50
Example 2
25:17
Example 3
31:05
Example 4
35:56
Example 5
41:49
Polar Equations & Functions

38m 16s

Intro
0:00
Introduction
0:04
Equations and Functions
1:16
Independent Variable
1:21
Dependent Variable
1:30
Examples
1:46
Always Assume That θ Is In Radians
2:44
Graphing in Polar Coordinates
3:29
Graph is the Same Way We Graph 'Normal' Stuff
3:32
Example
3:52
Graphing in Polar - Example, Cont.
6:45
Tips for Graphing
9:23
Notice Patterns
10:19
Repetition
13:39
Graphing Equations of One Variable
14:39
Converting Coordinate Types
16:16
Use the Same Conversion Formulas From the Previous Lesson
16:23
Interesting Graphs
17:48
Example 1
18:03
Example 2
18:34
Graphing Calculators, Yay!
19:07
Plot Random Things, Alter Equations You Understand, Get a Sense for How Polar Stuff Works
19:11
Check Out the Appendix
19:26
Example 1
21:36
Example 2
28:13
Example 3
34:24
Example 4
35:52
XII. Complex Numbers and Polar Coordinates
Polar Form of Complex Numbers

40m 43s

Intro
0:00
Polar Coordinates
0:49
Rectangular Form
0:52
Polar Form
1:25
R and Theta
1:51
Polar Form Conversion
2:27
R and Theta
2:35
Optimal Values
4:05
Euler's Formula
4:25
Multiplying Two Complex Numbers in Polar Form
6:10
Multiply r's Together and Add Exponents
6:32
Example 1: Convert Rectangular to Polar Form
7:17
Example 2: Convert Polar to Rectangular Form
13:49
Example 3: Multiply Two Complex Numbers
17:28
Extra Example 1: Convert Between Rectangular and Polar Forms
-1
Extra Example 2: Simplify Expression to Polar Form
-2
DeMoivre's Theorem

57m 37s

Intro
0:00
Introduction to DeMoivre's Theorem
0:10
n nth Roots
3:06
DeMoivre's Theorem: Finding nth Roots
3:52
Relation to Unit Circle
6:29
One nth Root for Each Value of k
7:11
Example 1: Convert to Polar Form and Use DeMoivre's Theorem
8:24
Example 2: Find Complex Eighth Roots
15:27
Example 3: Find Complex Roots
27:49
Extra Example 1: Convert to Polar Form and Use DeMoivre's Theorem
-1
Extra Example 2: Find Complex Fourth Roots
-2
XIII. Counting & Probability
Counting

31m 36s

Intro
0:00
Introduction
0:08
Combinatorics
0:56
Definition: Event
1:24
Example
1:50
Visualizing an Event
3:02
Branching line diagram
3:06
Addition Principle
3:40
Example
4:18
Multiplication Principle
5:42
Example
6:24
Pigeonhole Principle
8:06
Example
10:26
Draw Pictures
11:06
Example 1
12:02
Example 2
14:16
Example 3
17:34
Example 4
21:26
Example 5
25:14
Permutations & Combinations

44m 3s

Intro
0:00
Introduction
0:08
Permutation
0:42
Combination
1:10
Towards a Permutation Formula
2:38
How Many Ways Can We Arrange the Letters A, B, C, D, and E?
3:02
Towards a Permutation Formula, cont.
3:34
Factorial Notation
6:56
Symbol Is '!'
6:58
Examples
7:32
Permutation of n Objects
8:44
Permutation of r Objects out of n
9:04
What If We Have More Objects Than We Have Slots to Fit Them Into?
9:46
Permutation of r Objects Out of n, cont.
10:28
Distinguishable Permutations
14:46
What If Not All Of the Objects We're Permuting Are Distinguishable From Each Other?
14:48
Distinguishable Permutations, cont.
17:04
Combinations
19:04
Combinations, cont.
20:56
Example 1
23:10
Example 2
26:16
Example 3
28:28
Example 4
31:52
Example 5
33:58
Example 6
36:34
Probability

36m 58s

Intro
0:00
Introduction
0:06
Definition: Sample Space
1:18
Event = Something Happening
1:20
Sample Space
1:36
Probability of an Event
2:12
Let E Be An Event and S Be The Corresponding Sample Space
2:14
'Equally Likely' Is Important
3:52
Fair and Random
5:26
Interpreting Probability
6:34
How Can We Interpret This Value?
7:24
We Can Represent Probability As a Fraction, a Decimal, Or a Percentage
8:04
One of Multiple Events Occurring
9:52
Mutually Exclusive Events
10:38
What If The Events Are Not Mutually Exclusive?
12:20
Taking the Possibility of Overlap Into Account
13:24
An Event Not Occurring
17:14
Complement of E
17:22
Independent Events
19:36
Independent
19:48
Conditional Events
21:28
What Is The Events Are Not Independent Though?
21:30
Conditional Probability
22:16
Conditional Events, cont.
23:51
Example 1
25:27
Example 2
27:09
Example 3
28:57
Example 4
30:51
Example 5
34:15
XIV. Conic Sections
Parabolas

41m 27s

Intro
0:00
What is a Parabola?
0:20
Definition of a Parabola
0:29
Focus
0:59
Directrix
1:15
Axis of Symmetry
3:08
Vertex
3:33
Minimum or Maximum
3:44
Standard Form
4:59
Horizontal Parabolas
5:08
Vertex Form
5:19
Upward or Downward
5:41
Example: Standard Form
6:06
Graphing Parabolas
8:31
Shifting
8:51
Example: Completing the Square
9:22
Symmetry and Translation
12:18
Example: Graph Parabola
12:40
Latus Rectum
17:13
Length
18:15
Example: Latus Rectum
18:35
Horizontal Parabolas
18:57
Not Functions
20:08
Example: Horizontal Parabola
21:21
Focus and Directrix
24:11
Horizontal
24:48
Example 1: Parabola Standard Form
25:12
Example 2: Graph Parabola
30:00
Example 3: Graph Parabola
33:13
Example 4: Parabola Equation
37:28
Circles

21m 3s

Intro
0:00
What are Circles?
0:08
Example: Equidistant
0:17
Radius
0:32
Equation of a Circle
0:44
Example: Standard Form
1:11
Graphing Circles
1:47
Example: Circle
1:56
Center Not at Origin
3:07
Example: Completing the Square
3:51
Example 1: Equation of Circle
6:44
Example 2: Center and Radius
11:51
Example 3: Radius
15:08
Example 4: Equation of Circle
16:57
Ellipses

46m 51s

Intro
0:00
What Are Ellipses?
0:11
Foci
0:23
Properties of Ellipses
1:43
Major Axis, Minor Axis
1:47
Center
1:54
Length of Major Axis and Minor Axis
3:21
Standard Form
5:33
Example: Standard Form of Ellipse
6:09
Vertical Major Axis
9:14
Example: Vertical Major Axis
9:46
Graphing Ellipses
12:51
Complete the Square and Symmetry
13:00
Example: Graphing Ellipse
13:16
Equation with Center at (h, k)
19:57
Horizontal and Vertical
20:14
Difference
20:27
Example: Center at (h, k)
20:55
Example 1: Equation of Ellipse
24:05
Example 2: Equation of Ellipse
27:57
Example 3: Equation of Ellipse
32:32
Example 4: Graph Ellipse
38:27
Hyperbolas

38m 15s

Intro
0:00
What are Hyperbolas?
0:12
Two Branches
0:18
Foci
0:38
Properties
2:00
Transverse Axis and Conjugate Axis
2:06
Vertices
2:46
Length of Transverse Axis
3:14
Distance Between Foci
3:31
Length of Conjugate Axis
3:38
Standard Form
5:45
Vertex Location
6:36
Known Points
6:52
Vertical Transverse Axis
7:26
Vertex Location
7:50
Asymptotes
8:36
Vertex Location
8:56
Rectangle
9:28
Diagonals
10:29
Graphing Hyperbolas
12:58
Example: Hyperbola
13:16
Equation with Center at (h, k)
16:32
Example: Center at (h, k)
17:21
Example 1: Equation of Hyperbola
19:20
Example 2: Equation of Hyperbola
22:48
Example 3: Graph Hyperbola
26:05
Example 4: Equation of Hyperbola
36:29
Conic Sections

18m 43s

Intro
0:00
Conic Sections
0:16
Double Cone Sections
0:24
Standard Form
1:27
General Form
1:37
Identify Conic Sections
2:16
B = 0
2:50
X and Y
3:22
Identify Conic Sections, Cont.
4:46
Parabola
5:17
Circle
5:51
Ellipse
6:31
Hyperbola
7:10
Example 1: Identify Conic Section
8:01
Example 2: Identify Conic Section
11:03
Example 3: Identify Conic Section
11:38
Example 4: Identify Conic Section
14:50
XV. Sequences, Series, & Induction
Introduction to Sequences

57m 45s

Intro
0:00
Introduction
0:06
Definition: Sequence
0:28
Infinite Sequence
2:08
Finite Sequence
2:22
Length
2:58
Formula for the nth Term
3:22
Defining a Sequence Recursively
5:54
Initial Term
7:58
Sequences and Patterns
10:40
First, Identify a Pattern
12:52
How to Get From One Term to the Next
17:38
Tips for Finding Patterns
19:52
More Tips for Finding Patterns
24:14
Even More Tips
26:50
Example 1
30:32
Example 2
34:54
Fibonacci Sequence
34:55
Example 3
38:40
Example 4
45:02
Example 5
49:26
Example 6
51:54
Introduction to Series

40m 27s

Intro
0:00
Introduction
0:06
Definition: Series
1:20
Why We Need Notation
2:48
Simga Notation (AKA Summation Notation)
4:44
Thing Being Summed
5:42
Index of Summation
6:21
Lower Limit of Summation
7:09
Upper Limit of Summation
7:23
Sigma Notation, Example
7:36
Sigma Notation for Infinite Series
9:08
How to Reindex
10:58
How to Reindex, Expanding
12:56
How to Reindex, Substitution
16:46
Properties of Sums
19:42
Example 1
23:46
Example 2
25:34
Example 3
27:12
Example 4
29:54
Example 5
32:06
Example 6
37:16
Arithmetic Sequences & Series

31m 36s

Intro
0:00
Introduction
0:05
Definition: Arithmetic Sequence
0:47
Common Difference
1:13
Two Examples
1:19
Form for the nth Term
2:14
Recursive Relation
2:33
Towards an Arithmetic Series Formula
5:12
Creating a General Formula
10:09
General Formula for Arithmetic Series
14:23
Example 1
15:46
Example 2
17:37
Example 3
22:21
Example 4
24:09
Example 5
27:14
Geometric Sequences & Series

39m 27s

Intro
0:00
Introduction
0:06
Definition
0:48
Form for the nth Term
2:42
Formula for Geometric Series
5:16
Infinite Geometric Series
11:48
Diverges
13:04
Converges
14:48
Formula for Infinite Geometric Series
16:32
Example 1
20:32
Example 2
22:02
Example 3
26:00
Example 4
30:48
Example 5
34:28
Mathematical Induction

49m 53s

Intro
0:00
Introduction
0:06
Belief Vs. Proof
1:22
A Metaphor for Induction
6:14
The Principle of Mathematical Induction
11:38
Base Case
13:24
Inductive Step
13:30
Inductive Hypothesis
13:52
A Remark on Statements
14:18
Using Mathematical Induction
16:58
Working Example
19:58
Finding Patterns
28:46
Example 1
30:17
Example 2
37:50
Example 3
42:38
The Binomial Theorem

1h 13m 13s

Intro
0:00
Introduction
0:06
We've Learned That a Binomial Is An Expression That Has Two Terms
0:07
Understanding Binomial Coefficients
1:20
Things We Notice
2:24
What Goes In the Blanks?
5:52
Each Blank is Called a Binomial Coefficient
6:18
The Binomial Theorem
6:38
Example
8:10
The Binomial Theorem, cont.
10:46
We Can Also Write This Expression Compactly Using Sigma Notation
12:06
Proof of the Binomial Theorem
13:22
Proving the Binomial Theorem Is Within Our Reach
13:24
Pascal's Triangle
15:12
Pascal's Triangle, cont.
16:12
Diagonal Addition of Terms
16:24
Zeroth Row
18:04
First Row
18:12
Why Do We Care About Pascal's Triangle?
18:50
Pascal's Triangle, Example
19:26
Example 1
21:26
Example 2
24:34
Example 3
28:34
Example 4
32:28
Example 5
37:12
Time for the Fireworks!
43:38
Proof of the Binomial Theorem
43:44
We'll Prove This By Induction
44:04
Proof (By Induction)
46:36
Proof, Base Case
47:00
Proof, Inductive Step - Notation Discussion
49:22
Induction Step
49:24
Proof, Inductive Step - Setting Up
52:26
Induction Hypothesis
52:34
What We What To Show
52:44
Proof, Inductive Step - Start
54:18
Proof, Inductive Step - Middle
55:38
Expand Sigma Notations
55:48
Proof, Inductive Step - Middle, cont.
58:40
Proof, Inductive Step - Checking In
1:01:08
Let's Check In With Our Original Goal
1:01:12
Want to Show
1:01:18
Lemma - A Mini Theorem
1:02:18
Proof, Inductive Step - Lemma
1:02:52
Proof of Lemma: Let's Investigate the Left Side
1:03:08
Proof, Inductive Step - Nearly There
1:07:54
Proof, Inductive Step - End!
1:09:18
Proof, Inductive Step - End!, cont.
1:11:01
XVI. Preview of Calculus
Idea of a Limit

40m 22s

Intro
0:00
Introduction
0:05
Motivating Example
1:26
Fuzzy Notion of a Limit
3:38
Limit is the Vertical Location a Function is Headed Towards
3:44
Limit is What the Function Output is Going to Be
4:15
Limit Notation
4:33
Exploring Limits - 'Ordinary' Function
5:26
Test Out
5:27
Graphing, We See The Answer Is What We Would Expect
5:44
Exploring Limits - Piecewise Function
6:45
If We Modify the Function a Bit
6:49
Exploring Limits - A Visual Conception
10:08
Definition of a Limit
12:07
If f(x) Becomes Arbitrarily Close to Some Number L as x Approaches Some Number c, Then the Limit of f(x) As a Approaches c is L.
12:09
We Are Not Concerned with f(x) at x=c
12:49
We Are Considering x Approaching From All Directions, Not Just One Side
13:10
Limits Do Not Always Exist
15:47
Finding Limits
19:49
Graphs
19:52
Tables
21:48
Precise Methods
24:53
Example 1
26:06
Example 2
27:39
Example 3
30:51
Example 4
33:11
Example 5
37:07
Formal Definition of a Limit

57m 11s

Intro
0:00
Introduction
0:06
New Greek Letters
2:42
Delta
3:14
Epsilon
3:46
Sometimes Called the Epsilon-Delta Definition of a Limit
3:56
Formal Definition of a Limit
4:22
What does it MEAN!?!?
5:00
The Groundwork
5:38
Set Up the Limit
5:39
The Function is Defined Over Some Portion of the Reals
5:58
The Horizontal Location is the Value the Limit Will Approach
6:28
The Vertical Location L is Where the Limit Goes To
7:00
The Epsilon-Delta Part
7:26
The Hard Part is the Second Part of the Definition
7:30
Second Half of Definition
10:04
Restrictions on the Allowed x Values
10:28
The Epsilon-Delta Part, cont.
13:34
Sherlock Holmes and Dr. Watson
15:08
The Adventure of the Delta-Epsilon Limit
15:16
Setting
15:18
We Begin By Setting Up the Game As Follows
15:52
The Adventure of the Delta-Epsilon, cont.
17:24
This Game is About Limits
17:46
What If I Try Larger?
19:39
Technically, You Haven't Proven the Limit
20:53
Here is the Method
21:18
What We Should Concern Ourselves With
22:20
Investigate the Left Sides of the Expressions
25:24
We Can Create the Following Inequalities
28:08
Finally…
28:50
Nothing Like a Good Proof to Develop the Appetite
30:42
Example 1
31:02
Example 1, cont.
36:26
Example 2
41:46
Example 2, cont.
47:50
Finding Limits

32m 40s

Intro
0:00
Introduction
0:08
Method - 'Normal' Functions
2:04
The Easiest Limits to Find
2:06
It Does Not 'Break'
2:18
It Is Not Piecewise
2:26
Method - 'Normal' Functions, Example
3:38
Method - 'Normal' Functions, cont.
4:54
The Functions We're Used to Working With Go Where We Expect Them To Go
5:22
A Limit is About Figuring Out Where a Function is 'Headed'
5:42
Method - Canceling Factors
7:18
One Weird Thing That Often Happens is Dividing By 0
7:26
Method - Canceling Factors, cont.
8:16
Notice That The Two Functions Are Identical With the Exception of x=0
8:20
Method - Canceling Factors, cont.
10:00
Example
10:52
Method - Rationalization
12:04
Rationalizing a Portion of Some Fraction
12:05
Conjugate
12:26
Method - Rationalization, cont.
13:14
Example
13:50
Method - Piecewise
16:28
The Limits of Piecewise Functions
16:30
Example 1
17:42
Example 2
18:44
Example 3
20:20
Example 4
22:24
Example 5
24:24
Example 6
27:12
Continuity & One-Sided Limits

32m 43s

Intro
0:00
Introduction
0:06
Motivating Example
0:56
Continuity - Idea
2:14
Continuous Function
2:18
All Parts of Function Are Connected
2:28
Function's Graph Can Be Drawn Without Lifting Pencil
2:36
There Are No Breaks or Holes in Graph
2:56
Continuity - Idea, cont.
3:38
We Can Interpret the Break in the Continuity of f(x) as an Issue With the Function 'Jumping'
3:52
Continuity - Definition
5:16
A Break in Continuity is Caused By the Limit Not Matching Up With What the Function Does
5:18
Discontinuous
6:02
Discontinuity
6:10
Continuity and 'Normal' Functions
6:48
Return of the Motivating Example
8:14
One-Sided Limit
8:48
One-Sided Limit - Definition
9:16
Only Considers One Side
9:20
Be Careful to Keep Track of Which Symbol Goes With Which Side
10:06
One-Sided Limit - Example
10:50
There Does Not Necessarily Need to Be a Connection Between Left or Right Side Limits
11:16
Normal Limits and One-Sided Limits
12:08
Limits of Piecewise Functions
14:12
'Breakover' Points
14:22
We Find the Limit of a Piecewise Function By Checking If the Left and Right Side Limits Agree With Each Other
15:34
Example 1
16:40
Example 2
18:54
Example 3
22:00
Example 4
26:36
Limits at Infinity & Limits of Sequences

32m 49s

Intro
0:00
Introduction
0:06
Definition: Limit of a Function at Infinity
1:44
A Limit at Infinity Works Very Similarly to How a Normal Limit Works
2:38
Evaluating Limits at Infinity
4:08
Rational Functions
4:17
Examples
4:30
For a Rational Function, the Question Boils Down to Comparing the Long Term Growth Rates of the Numerator and Denominator
5:22
There are Three Possibilities
6:36
Evaluating Limits at Infinity, cont.
8:08
Does the Function Grow Without Bound? Will It 'Settle Down' Over Time?
10:06
Two Good Ways to Think About This
10:26
Limit of a Sequence
12:20
What Value Does the Sequence Tend to Do in the Long-Run?
12:41
The Limit of a Sequence is Very Similar to the Limit of a Function at Infinity
12:52
Numerical Evaluation
14:16
Numerically: Plug in Numbers and See What Comes Out
14:24
Example 1
16:42
Example 2
21:00
Example 3
22:08
Example 4
26:14
Example 5
28:10
Example 6
31:06
Instantaneous Slope & Tangents (Derivatives)

51m 13s

Intro
0:00
Introduction
0:08
The Derivative of a Function Gives Us a Way to Talk About 'How Fast' the Function If Changing
0:16
Instantaneous Slop
0:22
Instantaneous Rate of Change
0:28
Slope
1:24
The Vertical Change Divided by the Horizontal
1:40
Idea of Instantaneous Slope
2:10
What If We Wanted to Apply the Idea of Slope to a Non-Line?
2:14
Tangent to a Circle
3:52
What is the Tangent Line for a Circle?
4:42
Tangent to a Curve
5:20
Towards a Derivative - Average Slope
6:36
Towards a Derivative - Average Slope, cont.
8:20
An Approximation
11:24
Towards a Derivative - General Form
13:18
Towards a Derivative - General Form, cont.
16:46
An h Grows Smaller, Our Slope Approximation Becomes Better
18:44
Towards a Derivative - Limits!
20:04
Towards a Derivative - Limits!, cont.
22:08
We Want to Show the Slope at x=1
22:34
Towards a Derivative - Checking Our Slope
23:12
Definition of the Derivative
23:54
Derivative: A Way to Find the Instantaneous Slope of a Function at Any Point
23:58
Differentiation
24:54
Notation for the Derivative
25:58
The Derivative is a Very Important Idea In Calculus
26:04
The Important Idea
27:34
Why Did We Learn the Formal Definition to Find a Derivative?
28:18
Example 1
30:50
Example 2
36:06
Example 3
40:24
The Power Rule
44:16
Makes It Easier to Find the Derivative of a Function
44:24
Examples
45:04
n Is Any Constant Number
45:46
Example 4
46:26
Area Under a Curve (Integrals)

45m 26s

Intro
0:00
Introduction
0:06
Integral
0:12
Idea of Area Under a Curve
1:18
Approximation by Rectangles
2:12
The Easiest Way to Find Area is With a Rectangle
2:18
Various Methods for Choosing Rectangles
4:30
Rectangle Method - Left-Most Point
5:12
The Left-Most Point
5:16
Rectangle Method - Right-Most Point
5:58
The Right-Most Point
6:00
Rectangle Method - Mid-Point
6:42
Horizontal Mid-Point
6:48
Rectangle Method - Maximum (Upper Sum)
7:34
Maximum Height
7:40
Rectangle Method - Minimum
8:54
Minimum Height
9:02
Evaluating the Area Approximation
10:08
Split the Interval Into n Sub-Intervals
10:30
More Rectangles, Better Approximation
12:14
The More We Us , the Better Our Approximation Becomes
12:16
Our Approximation Becomes More Accurate as the Number of Rectangles n Goes Off to Infinity
12:44
Finding Area with a Limit
13:08
If This Limit Exists, It Is Called the Integral From a to b
14:08
The Process of Finding Integrals is Called Integration
14:22
The Big Reveal
14:40
The Integral is Based on the Antiderivative
14:46
The Big Reveal - Wait, Why?
16:28
The Rate of Change for the Area is Based on the Height of the Function
16:50
Height is the Derivative of Area, So Area is Based on the Antiderivative of Height
17:50
Example 1
19:06
Example 2
22:48
Example 3
29:06
Example 3, cont.
35:14
Example 4
40:14
XVII. Appendix: Graphing Calculators
Buying a Graphing Calculator

10m 41s

Intro
0:00
Should You Buy?
0:06
Should I Get a Graphing Utility?
0:20
Free Graphing Utilities - Web Based
0:38
Personal Favorite: Desmos
0:58
Free Graphing Utilities - Offline Programs
1:18
GeoGebra
1:31
Microsoft Mathematics
1:50
Grapher
2:18
Other Graphing Utilities - Tablet/Phone
2:48
Should You Buy a Graphing Calculator?
3:22
The Only Real Downside
4:10
Deciding on Buying
4:20
If You Plan on Continuing in Math and/or Science
4:26
If Money is Not Particularly Tight for You
4:32
If You Don't Plan to Continue in Math and Science
5:02
If You Do Plan to Continue and Money Is Tight
5:28
Which to Buy
5:44
Which Graphing Calculator is Best?
5:46
Too Many Factors
5:54
Do Your Research
6:12
The Old Standby
7:10
TI-83 (Plus)
7:16
TI-84 (Plus)
7:18
Tips for Purchasing
9:17
Buy Online
9:19
Buy Used
9:35
Ask Around
10:09
Graphing Calculator Basics

10m 51s

Intro
0:00
Read the Manual
0:06
Skim It
0:20
Play Around and Experiment
0:34
Syntax
0:40
Definition of Syntax in English and Math
0:46
Pay Careful Attention to Your Syntax When Working With a Calculator
2:08
Make Sure You Use Parentheses to Indicate the Proper Order of Operations
2:16
Think About the Results
3:54
Settings
4:58
You'll Almost Never Need to Change the Settings on Your Calculator
5:00
Tell Calculator In Settings Whether the Angles Are In Radians or Degrees
5:26
Graphing Mode
6:32
Error Messages
7:10
Don't Panic
7:11
Internet Search
7:32
So Many Things
8:14
More Powerful Than You Realize
8:18
Other Things Your Graphing Calculator Can Do
8:24
Playing Around
9:16
Graphing Functions, Window Settings, & Table of Values

10m 38s

Intro
0:00
Graphing Functions
0:18
Graphing Calculator Expects the Variable to Be x
0:28
Syntax
0:58
The Syntax We Choose Will Affect How the Function Graphs
1:00
Use Parentheses
1:26
The Viewing Window
2:00
One of the Most Important Ideas When Graphing Is To Think About The Viewing Window
2:01
For Example
2:30
The Viewing Window, cont.
2:36
Window Settings
3:24
Manually Choose Window Settings
4:20
x Min
4:40
x Max
4:42
y Min
4:44
y Max
4:46
Changing the x Scale or y Scale
5:08
Window Settings, cont.
5:44
Table of Values
7:38
Allows You to Quickly Churn Out Values for Various Inputs
7:42
For example
7:44
Changing the Independent Variable From 'Automatic' to 'Ask'
8:50
Finding Points of Interest

9m 45s

Intro
0:00
Points of Interest
0:06
Interesting Points on the Graph
0:11
Roots/Zeros (Zero)
0:18
Relative Minimums (Min)
0:26
Relative Maximums (Max)
0:32
Intersections (Intersection)
0:38
Finding Points of Interest - Process
1:48
Graph the Function
1:49
Adjust Viewing Window
2:12
Choose Point of Interest Type
2:54
Identify Where Search Should Occur
3:04
Give a Guess
3:36
Get Result
4:06
Advanced Technique: Arbitrary Solving
5:10
Find Out What Input Value Causes a Certain Output
5:12
For Example
5:24
Advanced Technique: Calculus
7:18
Derivative
7:22
Integral
7:30
But How Do You Show Work?
8:20
Parametric & Polar Graphs

7m 8s

Intro
0:00
Change Graph Type
0:08
Located in General 'Settings'
0:16
Graphing in Parametric
1:06
Set Up Both Horizontal Function and Vertical Function
1:08
For Example
2:04
Graphing in Polar
4:00
For Example
4:28
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Lecture Comments (12)

1 answer

Last reply by: Professor Selhorst-Jones
Wed May 20, 2015 11:09 AM

Post by Carolyn Miller on May 18, 2015

In Example 5 part A. wouldn't it also be possible to get the answer by converting it to exponential form(?)? Or would I not be able to use it for all problems, only for a few like the one used?

1 answer

Last reply by: Professor Selhorst-Jones
Sun Nov 9, 2014 4:36 PM

Post by Saadman Elman on November 8, 2014

A great clarification! Although example 5 didn't make sense. As you said, you are going to do logarithm equation in the next chapter.  I Will listen to it soon. Thanks!

1 answer

Last reply by: Professor Selhorst-Jones
Sun Dec 22, 2013 1:12 PM

Post by Tim Zhang on December 18, 2013

a^b=x , why "a" must greater than zero?? can't a be negative? like when a equal -5, you can still get the value of x right?

1 answer

Last reply by: Professor Selhorst-Jones
Tue Nov 19, 2013 5:47 PM

Post by Constance Kang on November 17, 2013

hey, for example 3, you said we could make u be anything right? so i made u=10 and when i put it into calculator log(42)-log(7), i end up getting 0.7781512504. What did i do wrong?

3 answers

Last reply by: Professor Selhorst-Jones
Mon Aug 12, 2013 1:40 PM

Post by Taylor Wright on July 25, 2013

Since Log(base a) of a   is equal to 1

Why wouldn't Log(base a) of a^b  equal   1^b



Therefore making  a^Log(base a) of a^b  equal to a^1^b  

Properties of Logarithms

  • We defined the idea of a logarithm in the previous lesson. A logarithm is the inverse of exponentiation:
    loga x = y     ⇔     ay = x.
    Since logarithms and exponents are so deeply connected, we might expect logarithms to have some interesting properties, just like we discovered how exponents have many interesting properties.
  • If you're interested in understanding how we figure out any of the below properties, check out the video for an explanation.
  • From the definition of a logarithm, we can immediately find two basic properties:
    loga 1 = 0                      loga a = 1
  • Logarithms and exponentiation are inverse processes: they "cancel" each other out.
    loga ax = x                      aloga x = x
  • If we take the logarithm of a power, we can "bring the power down" in front of the logarithm:
    loga xn  =  n·loga x.
  • If we have the logarithm of a product, we can split it through addition of logarithms:
    loga (M ·N)   =  loga M + loga N.
  • If we have the logarithm of a quotient, we can split it through subtraction of logarithms:
    loga
    M

    N


     



     
    =  loga M − loga N.
  • Caution! Notice that none of these properties were ever of the form loga (M+N). That's because there is just no nice formula to break apart loga (M+N).
  • If we have a logarithm that uses a different base than we want, we can change it through the change of base formula:
    logv x =logu x

    logu v


     
    .
    Notice how this allows us to change from an expression logv x to an expression that only uses logu . By using u = e or u=10, we can evaluate with any calculator.

Properties of Logarithms

Expand the below as much as possible to write it as a sum and/or difference of logarithms.
log7 (x2 ·y)
  • From the logarithm properties, we have loga (M ·N) = loga M + loga N. Thus, we can split the expression as
    log7 (x2 ·y)     =     log7 x2 + log7 y
  • We also have the property loga xn = n ·loga x, allowing us to expand it even further.
    log7 x2 + log7 y     =     2 ·log7 x + log7 y
    All the logarithms have been expanded as much as they possibly can be, so we are now finished.
2 ·log7 x + log7 y
Expand the below as much as possible to write it as a sum and/or difference of logarithms.
ln

a5
4
 
 

b3

c2+5
 


  • From the logarithm properties, we have loga (M ·N) = loga M + loga N. Thus, we can split the expression as
    ln

    a5
    4
     
     

    b3

    c2+5
     


        =     lna5 + ln
    4
     
     

    b3

    c2+5
     
  • We also have the property loga xn = n ·loga x, allowing us to expand it even further. [Remember, 4√{k} = k[1/4]]
    lna5 + ln
    4
     
     

    b3

    c2+5
     
        =     5 ·lna + 1

    4
    ·ln b3

    c2+5
  • Next, we have a property that allows us to separate fractions: loga ( [M/N] ) = loga M − loga N. This gives us
    5 ·lna + 1

    4
    ·ln b3

    c2+5
        =    5 ·lna + 1

    4
    ·
    lnb3 − ln(c2+5)
  • Remember, there is no rule to separate loga (M+N), so while it may look like we could separate ln(c2+5) further, it is actually impossible. We must leave ln(c2+5) as it is because there is no rule we can expand it further with.
  • We can do a little bit more with the other expressions, though. Begin by distributing the [1/4]:
    5 ·lna + 1

    4
    ·
    lnb3 − ln(c2+5)
        =    5 ·lna + 1

    4
    ·lnb3 1

    4
    ·ln(c2+5)
    Then use the rule about exponents one more time:
    5 ·lna + 1

    4
    ·lnb3 1

    4
    ·ln(c2+5)     =    5 ·lna + 3

    4
    ·lnb − 1

    4
    ·ln(c2+5)
    All the logarithms have been expanded as much as they possibly can be, so we are now finished.
5 ·lna + [3/4] ·lnb − [1/4] ·ln(c2+5)
Find the exact value of the below.
log4.7 4.719
  • From the properties, we know that a logarithm of a given base cancels out exponentiation of the same base. That is,
    loga ax = x
  • Thus, since we have log4.7 and an exponentiation with a base of 4.7, the two cancel each other out and all we are left with is the power:
    log4.7 4.719 = 19
19
Give an example of two numbers that show how, in general,
loga (M+N) ≠ loga M + loga N
  • To show this, we can basically pick any numbers we want for a, M, and N to show that loga (M+N) will not be equal to loga M + loga N. However, to make it easier for us to show, it would be nice to pick some numbers that simplify in a "friendly" way to make it obvious that the two sides are not equal.
  • A "friendly" set of numbers to choose is a=2 (an easy base to work with) along with M=N=4 (a number that is easy to calculate log2 of).
  • With these numbers in mind, try plugging them in for each side:
    loga (M+N)     =     log2 (4+4)     =     log2 8     =     log2 23     =     3
    Plugging in for the other side, we have:
    loga M + loga N     =     log2 4 + log2 4     =     log2 22 + log2 22     =     2+2     =     4
    Since 3 ≠ 4, we have now shown how loga (M+N) ≠ loga M + loga N is true in general.
  • Detailed Explanation: While the above is one way to show things, there are many possible ways. You can choose virtually any combination of values for a, M, and N (assuming they are all greater than 0, otherwise you will break the logarithm) to show the expression is true. In fact, the only way loga (M+N) ≠ loga M + loga N can fail to be true is if you choose your M and N very carefully (the choice of a has no effect, either way). For the non-equality to be true, the two sides must be equal:
    loga (M+N) = loga M + loga N
    However, from other logarithm properties, we know loga M + loga N = loga (M·N). So,
    loga (M+N) = loga (M·N)
    Which means that the only way for loga (M+N) ≠ loga M + loga N to not be true is if you carefully choose your M and N values such that
    M+N = M ·N
    Thus, as long as you don't carefully choose your M and N values to make the above equation true (and/or you are not extremely unlucky in your random choice of values), whatever you pick is almost guaranteed to show that loga (M+N) ≠ loga M + loga N is true in general.
There are many, many possible ways to show this. One such way is
log2 (4+4) ≠ log2 4 + log2 4
[If you're interested in a bit of discussion on the variety of possible ways to show how the expression loga (M+N) ≠ loga M + loga N is true in general, check out the last step.]
Given that log3 a = 5 and log3 b = 6, find the value of
log3 (3 ab)
  • Currently, the expression does not explicitly contain log3 a or log3 b, so we can't use either of the pieces of information given to us at the start of the question. However, if we could find a way to explicitly show those expressions inside of log3 (3 ab), then we could use them. We can work towards this by expanding the expression through the use of logarithm properties.
  • We can expand the expression using the rule loga (M ·N) = loga M + loga N:
    log3 (3 ab)     =     log3 3 + log3 a + log3 b
  • Now we clearly and explicitly have log3 a and log3 b in the expression, so we can substitute in the values we were given:
    log3 3 + 5 + 6
  • Finally, we need to figure out what the value of log3 3 is. This is pretty easy, since loga a = 1 for any a. Thus, we have
    log3 3 + 5 + 6     =     1 + 5 + 6     =     12
12
Given that ln√x = 3 and lny = 1.6, find the value of
ln
x2

y5

  • First off, it will help us to know what the values of lnx and lny are. We already know lny = 1.6, but we don't know lnx yet. To figure that out, notice that we do know ln√x = 3 and we have the rule that loga xn = n ·loga x. Thus, we can show
    ln√x = 3     ⇒     lnx[1/2] = 3     ⇒     1

    2
    ·lnx = 3     ⇒     lnx = 6
  • Currently, the expression does not explicitly contain lnx or lny, so we can't use either of those pieces of information. However, if we could find a way to explicitly show those expressions inside of what the question gave us, then we could use them. We can work towards this by expanding the expression through the use of logarithm properties.
  • We can expand the expression using the rule loga ( [M/N] ) = loga M − loga N:
    ln
    x2

    y5

        =     lnx2 − lny5
    Then, using the rule that loga xn = n ·loga x, we can show
    lnx2 − lny5     =     2 ·lnx − 5 ·lny
  • Now we clearly and explicitly have lnx and lny in the expression, so we can substitute in the values we know:
    2 ·lnx − 5 ·lny     =     2 ·6 − 5 ·1.6     =     12 − 8     =     4
4
Write the expression as a single logarithm.
3 lnu + 5 lnv
  • We want to condense the expression into a single logarithm using logarithm properties. We can begin by putting the coefficients inside the logarithms as exponents based on the property loga xn = n ·loga x:
    3 lnu + 5 lnv     =     lnu3 + lnv5
  • Next, we can combine the two logarithms with multiplication (because they're being added together) through the property loga (M ·N) = loga M + loga N:
    lnu3 + lnv5     =     ln( u3 v5 )
    At this point we're done, because everything is contained in a single logarithm. [It's important to notice that we could not have applied the properties in the opposite order. The property loga (M ·N) = loga M + loga N can only be applied when the logs do not have coefficients in front of them, so we had to move the coefficients out of the way with the other property first.]
ln( u3 v5 )
Write the expression as a single logarithm.
3 loga − 5

4
(logb − 2 logc)
  • Begin by distributing the fraction (along with the negative attached to it) so that we can clearly see how to properly apply the logarithm properties:
    3 loga − 5

    4
    (logb − 2 logc)     =     3 loga − 5

    4
    logb + 5

    2
    logc
  • We can now put the coefficients inside the logarithms as exponents based on the property loga xn = n ·loga x:
    loga3 − logb[5/4] + logc[5/2]
  • Next, we can combine the two logarithms that are adding together through the property loga (M ·N) = loga M + loga N:
    loga3 + logc[5/2]− logb[5/4]     =     log(a3 c[5/2] ) − logb[5/4]
  • Finally, we can combine the logarithm that is subtracting through the property loga ( [M/N] ) = loga M − loga N:
    log(a3 c[5/2] ) − logb[5/4]     =     log
    a3 c[5/2]

    b[5/4]

    At this point we're done, because everything is contained in a single logarithm.
log( [(a3 c[5/2])/(b[5/4])])
Evaluate the below (to three decimal places) using a calculator and the change of base formula.
log19 947
  • Most calculators only have two buttons for evaluating logarithms: ln and log (which respectively mean loge and log10). This means that if you want to evaluate a logarithm that has a different base than those two, you need a way to change the base of the logarithm. This is where the change of base formula comes in to play. [Some calculators can directly calculate the value of logarithms with bases other than e and 10. If you have such a calculator, congratulations!-You've got a real beast of a calculator. Nonetheless, play along with the below steps so that you can see how to change base in cases where the calculator can't help (like when working with variables).]
  • The change of base formula allows us to change from using the base v to the base u as below:
    logv x = logu x

    logu v
  • Thus, since we want to switch from the base of 19 to one of the bases on our calculator (e or 10-let's go with 10, just to make a choice for the below [although either is fine]), we can use the formula as follows:
    log19 947 = log10 947

    log10 19
  • Now we can use a calculator to find the value of both log10 947 and log10 19, then divide to find
    log10 947

    log10 19
    ≈ 2.328
2.328
Evaluate the below (to three decimal places) using a calculator and the change of base formula.
log√2 15
  • Most calculators only have two buttons for evaluating logarithms: ln and log (which respectively mean loge and log10). This means that if you want to evaluate a logarithm that has a different base than those two, you need a way to change the base of the logarithm. This is where the change of base formula comes in to play. [Some calculators can directly calculate the value of logarithms with bases other than e and 10. If you have such a calculator, congratulations!-You've got a real beast of a calculator. Nonetheless, play along with the below steps so that you can see how to change base in cases where the calculator can't help (like when working with variables).]
  • The change of base formula allows us to change from using the base v to the base u as below:
    logv x = logu x

    logu v
  • Thus, since we want to switch from the base of √2 to one of the bases on our calculator (e or 10-let's go with 10, just to make a choice for the below [although either is fine]), we can use the formula as follows:
    log√2 15 = log10 15

    log10 √2
  • Now we can use a calculator to find the value of both log10 15 and log10 √2, then divide to find
    log10 15

    log10 √2
    ≈ 7.814
    [If you have difficulty taking the log of √2 on your calculator (although it should work fine on the majority of calculators: just calculate √2, then take its log using the appropriate log button.), you can always use an accurate approximation of √2 in decimal form, then take its log.]
7.814

*These practice questions are only helpful when you work on them offline on a piece of paper and then use the solution steps function to check your answer.

Answer

Properties of Logarithms

Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.

  • Intro 0:00
  • Introduction 0:04
  • Basic Properties 1:12
  • Inverse--log(exp) 1:43
  • A Key Idea 2:44
    • What We Get through Exponentiation
    • B Always Exists
  • Inverse--exp(log) 5:53
  • Logarithm of a Power 7:44
  • Logarithm of a Product 10:07
  • Logarithm of a Quotient 13:48
  • Caution! There Is No Rule for loga(M+N) 16:12
  • Summary of Properties 17:42
  • Change of Base--Motivation 20:17
    • No Calculator Button
    • A Specific Example
    • Simplifying
  • Change of Base--Formula 24:14
  • Example 1 25:47
  • Example 2 29:08
  • Example 3 31:14
  • Example 4 34:13

Transcription: Properties of Logarithms

Hi--welcome back to Educator.com.0000

Today, we are going to talk about the properties of logarithms.0002

In the previous lesson, we introduced the idea of a logarithm, which was defined as loga(x) = y for ay = x.0005

So, the logarithm of a number is what we would have to raise the base to, to get the number.0015

So, loga(x) = y means ay = x.0022

It is a little bit of a complex idea the first time we talk about it, so the previous lesson is really useful.0027

If you haven't already watched the previous lesson, Introduction to Logarithms, I really recommend that you watch it,0032

because that will get you a grounding in how these things work--it will really explain things, if it is confusing you.0037

Previously, when we investigated exponentiation, we found all sorts of interesting properties,0042

such as xa times xb = xa + b--that we could add exponents--0046

or that x-a = 1/xa--that we flip when we have negative exponents.0051

Since logarithms and exponents are so deeply connected (we have this idea that log of something0057

equals this other version in exponent world), we might expect logarithms to also have some interesting properties.0061

Indeed, they do: this lesson will be all about looking at the properties of logarithms.0068

Let's just start with some really basic properties--remember, this is the definition that we will be working with the whole time.0073

It is a really good idea to understand this.0079

From this, we can immediately see two basic properties: loga(1) = 0, because a0 = 1 for anything;0082

that was one of the things that we figured out when we were working with exponents;0090

and also, loga(a) is going to equal 1, because a1 is just equal to a, because it is just 1a.0093

Those are two basic properties that we get, just from the simple definition.0100

Next, we can talk about inverses: logarithms and exponentiation are inverse processes.0104

If they have the same base, they cancel each other out.0109

This is clear when a logarithm acts on exponentiation; if we have loga(ax),0114

then we are going to get x out of it, because by the definition of a logarithm,0119

the number that we need to raise x to--what do we have to raise a to, to get ax?0123

Well, that is going to be ax; so a is our base for the right side; ax = ax, so loga(ax) = x.0129

It cancels out; a logarithm on exponentiation...they cancel each other out, because we have an a here and an a here as bases.0139

So, they cancel out, and we are left with just the x that we originally had.0147

So, logarithms cancel out exponentiation, if they are of the same base.0151

We just get left with the exponent at the end.0156

To see the reverse process of exponentiation, canceling a logarithm, we first need to realize a useful idea.0158

Notice that, for any exponent base where a is greater than 0, our exponent base is positive, and it is not equal to 1.0165

And for any number x such that x is a positive number, there exists some real number b such that ab = x.0171

In other words, through exponentiation, this a to the something, we can get to any positive number x.0180

For any positive number...you say 58 as your x...then with my a, I can raise it to something that will get it to 58.0185

And then, if we want, we can name the exponent that will do this; and we called it b here.0194

There is some number b such that ab = x.0198

So, for example, we could say that 10 to the something has to be equal to 100.0202

Our question is what number it is as our something: 10 to the what equals 100?0208

Well, it is going to be 2; we raise 10 to the 2--102--we get 100.0213

So, in this case, our b, if we want to name the number in the box, was 2.0218

We could do this for something else: we could say, "3 to the box equals 47."0223

Now, this is considerably more complex than 10 to box equals 100.0230

3 isn't going to have some nice integer, some nice even power, that we can raise it to, that will put out 47.0233

But we can note that there has to be something that fits in that box.0241

We don't know what the number is right now, but we are confident--we are sure that there has to be something that we could raise 3 to, to get 47.0244

So, we can just call it b; in fact, if you were to work it out through other stuff that we will talk about as we go on in this class,0251

if you were to work it out, you would find out that b is approximately equal to 3.504555.0258

If you plug that into a calculator, you will see that it is very, very close to being precisely 47.0266

So, there is some number out there; we can't get it exactly, but we can get a very good approximation through things that we work out in this course.0270

We can be sure that this number does exist--it is out there somewhere, even if we don't know it.0278

But that doesn't mean we can't talk about it; we can not know what something is precisely, and still talk about it as a general idea.0283

So, we know that this has to be true, because every exponential function, a to the something, has a range of 0 to infinity.0291

We have talked about this before, and you can see it in the graphs of it.0297

Since it has a range of 0 to infinity--since any number can come out of it, as long as it is a positive number--0300

then there has to be some b that will make that number from between 0 and infinity.0305

For any x contained in 0 to infinity, for any positive number x, there has to be some b that,0310

when we plug it in here, we will end up getting ab = x.0315

We will end up getting that x when we plug it in.0322

This idea that there is always an exponent for creating any positive number (it won't work if it is negative;0324

but for creating any number) is really important; we will use this fact to prove a variety of properties about logarithms.0329

So, we want to keep this idea that, if we have some x, and we know we have some base a,0335

then there has to exist some real number b to make ab = x.0340

So, you start with a base a; you start with some sort of destination x; you are guaranteed that there is a b that will get you to that destination through exponentiation.0345

With this idea in mind, we can now show inverses in the other direction.0354

Consider aloga(x): now, by our new idea, we know that there has to be some b such that ab = x.0359

Here is our x; and we just choose the base a--it is going to be connected to the fact that we have the base a here, showing up here.0368

So, we know that a to the something equals x; and we are guaranteed that there has to be some b there.0375

So, we are talking about it here: we know that there is some b such that ab = x.0381

So, we can say a to the loga of...and now we replace it with ab = x,0385

so we replace right here, and it becomes ab, so aloga(ab).0392

Now, we just showed that loga(ab) = b, because logs on exponents cancel out.0399

So, loga(ab) = b, so we have the same thing here.0406

loga(a) will drop us down to just having the b, so that b will move over to being the exponent, and we will have ab.0410

But how did we define ab in the first place? It was ab = x.0418

So, we know that ab = x; since we created b based on the fact that ab = x,0422

we have now shown that what we started with ends up being equivalent to x.0428

So, we have that a raised to the loga(x) is equal to x.0432

So now, at this point, we have shown inverses in both directions.0436

If you take log of an exponent, and they both have the same base, they cancel out, and we are just left with whatever was our power.0439

If we take some base and raise it, through exponentiation, to a log, and that base there and the base on the log are the same thing,0445

we end up just having what the log was taking as its quantity.0455

So, we have inverses shown in both ways; we can cancel out in both directions.0460

All right, we will move on to something else: the logarithm of a power.0465

Consider if we had some positive number x, and any real number n; then what if we raised to the n and took its log?0468

So, we have loga(xn); by our key idea,0473

we know that there exists some b such that we can write ab = x--the same thing.0478

So, if we want, we can swap out our x here for ab.0484

So, we have ab to the n now; from our rules about exponents, we know that ab to the n,0488

is the same thing as just a to the b times n; so now, we have b times n, or we could write it as n times b.0499

loga(a) to the n times b becomes canceled out, because we have inverses there,0506

since they are the same base, and we are left with n times b.0514

Now, do we have another way to express b?0517

Well, from the beginning, we know that ab = x, so we could write that in its logarithmic form.0519

And we would show that loga(x) = b, because ab = x.0525

If we move this over here, a raised to the b becomes x from how we had this originally.0534

So, we see that loga(x) = b, which means that we can swap the b out here for the loga(x).0539

And we have that loga(x) here; we started with loga(xn),0548

and now we see that we can take this n here and move it out front, and we have n times loga(x).0555

So, if we have an exponent, we can move it out front.0562

Let's look at an example: if we look at log3(32), by this property,0565

we see that we could take this 2 and move it out front, and we would have 2 times log3(3).0574

Well, log3(3)...log base something of something, if they are the same something...is just 1.0580

What do you have to raise 3 to, to get 3? Just 1.0587

So, we have 2 times 1, which is equal to 2.0590

What if we look at it the other way?0595

Well, log3(9)...what do we have to raise 3 to, to get 9?0596

We just have to raise it to 2; so we have 2 here and 2 here; either way we go at it, we end up getting the same thing.0600

We see this property in action.0606

OK, now let's consider two positive numbers, m and n (that should be "numbers, m and n"): loga(mn).0609

log base a of the whole quantity, m times n: now, from our key idea, we know that there exist m and n,0618

such that we can raise a to the m, and will get M; and we raise a to the n, and we get N.0624

So, we can swap these things out: we can swap out here, and we can swap out here.0631

And we end up getting loga(aman).0636

Now, from our work about exponents, we know that am times an is the same thing as am + n.0642

The same base means that we can add the exponents, so we have loga(am + n).0649

And then, since it is loga on an exponent base of a, we get cancellation once again through inverses;0655

loga cancels out with that, and we are left with just m + n.0661

Now, we can ask ourselves, "Do we have another way to express m and n?"0665

Well, from the beginning, we know that am = M; that was how we set this up.0668

So, loga(M) = m, because we know that if we raise a to the m, we get M; so we have that.0677

We can express it in its exponential form or its logarithmic form.0691

So we now can say, "What about looking at it through its logarithmic form?"0694

The same thing goes over here with an = N; we can express it, instead, as loga(N) = n.0697

So, at this point, we have two different new ways to be able to describe m + n.0705

We can swap that out; and so, loga(M) here becomes here, and loga(N) = n goes here.0712

So, you see this here; you see this here; we can swap that out.0723

So, what we started with, loga(MN), is going to be the same thing as loga(M) + loga(N).0729

So, if we have a logarithm of a product, we can split it into the sum of the logarithms of the numbers that made up each part of that product.0741

Let's look at an example to help clarify this.0753

We could look at log10; we will write it as just log, since the common log can be expressed as just log.0756

So, log(1000): we could write this, if we felt like it, as log(100 times 10).0768

And then, by this rule that we have here, we could split it; we have products 100 and 10, so we can split it into log(100) + log(10).0777

Now, what number do we have to raise 10 to, to get 100?0786

We have to raise it to 2; what number do we have to raise 10 to, to get 10? We only have to raise it to 1.0789

So, 2 + 1...we end up getting 3.0801

Alternatively, we could have done this as log(1000): what number do we have to raise 10 to, to get 1000?0804

10 is 1; 100 is 2; 1000 is at 3; so we could also see that log10(1000) = 3 over here.0810

So, it works out either way that we want to approach it.0820

So, we see now that we can break up products into two different things being added together.0822

What if we took the logarithm of a quotient, loga(M/N)?0829

Well, we could rewrite that as M times N-1, since we could rewrite M/N as M times 1/N.0833

And then, we can rewrite 1/N as just its flip, so we would have N-1.0843

We can swap it around like that.0848

From the rule that we just saw, the splitting of products, we can write this as...0850

here is the M, so we have loga(M); and here is the N-1, so we have loga(N-1).0855

So, loga(M)...and then, we also have our rule that we can bring down exponents.0861

log(xn) becomes nlog(x); so we bring this down in the front.0867

Since we are bringing down a -1, it just becomes a minus sign here; so we have loga(M) - loga(N).0873

Thus, loga(M/N) is equal to loga(M) - loga(N).0884

So, the logarithm of a quotient becomes the difference of the two logarithms.0889

Let's look at an example to help clarify this one, as well.0896

So, if we look at log2(32/2), we could write that, by our new rules, as log2(32)0899

(is the part on the top), and then the part on the bottom is 2, so minus log2(2).0911

log2(32): what number do we have to raise 2 to, to get 32?0920

Well, 2 is 1; 4 is 2; 8 is 3; 16 is 4; 32 is at 5--so we raise 2 to the 5, and we get 32; so log2(32) is 5.0924

What is log2(2)? -1: 2 to the 1 equals 2, so just 1; so 5 - 1...we end up getting 4.0937

What if we had looked at it, not through breaking it apart, but just simplified it first--32/2?0948

Well, we could write that as log2(16); what number do we need to raise 2 to, to get 16?0953

2 to the 1 becomes 2; 2 squared becomes 4; 2 to the 3 becomes 8; 2 to the 4 becomes 16; so this would end up being 4.0959

So, we end up getting the same thing, either way we look at it.0968

Great; I want to caution you that there is no rule for log(M + N).0971

Notice: none of these properties were ever of the form log(M + N) inside of there.0979

That is because there is just no nice formula to break apart log(M + N).0984

So, if you have a log of a quantity, and inside of that quantity it is something plus something else, there are no special rules.0989

Sorry--there is just no easy way around it; you are going to have to work things out there in a complicated way.0994

There is no way to be able to just break things apart or put things together anymore.0998

Lots of people make the mistake of thinking that loga(M + N) is equal to loga(M) + loga(N).1002

or that loga(M - N) is equal to loga(M) - loga(N).1007

Those are not true--not true at all; you can't write them and split them apart like this.1011

These things do not work; it is the same thing as, if you have √(2 + 2), saying, "Oh, I will just split that into √2 + √2."1017

That does not work; you can't just split on square roots; you can't just split on logarithms, either.1027

So, this idea of just splitting because you see an addition sign--you can't do that.1032

You have to work out what is the logarithm of everything inside of there; there are no clean rules to do that.1036

It is an easy mistake to end up making; but don't let it happen to you.1041

Be vigilant; watch out for this; don't let it happen to you; don't do the same mistake.1044

Remember, it only works with M times N and M divided by N.1048

If it is plus or minus, there are no special rules; you just have to work it out by figuring things out,1052

simplifying, hopefully, if you can, like they are actually numbers; but there is really no easy way around it.1056

At this point, we have seen a lot of properties for logarithms; so let's review them.1063

Our base ones right at the beginning were the log base any a of 1 equals 0,1065

because any a raised to the 0 becomes 1; and also, log base a of a equals 1, because any a raised to the 1 is just a.1071

Then, we also have our inverse properties, loga(ax) = x,1079

that it cancels out when you have logarithm on exponentiation if they are the same base;1083

and then a raised to the loga(x) = x when we have exponentiation acting on logarithms.1088

It cancels out if they are the same base.1092

Then, we have the fact that we can bring down powers.1095

If we have log(xn), then we can bring the n in front: we have n times log(x).1098

If we have log(MN), then we can split that into log(M) + log(N).1105

We have the two different pieces, M and N, so it splits into log(M) and log(N).1111

Multiplication inside of a logarithm becomes addition outside of the logarithm.1116

loga(M/N) is log(M) - log(N); if we have M here and N here, then we have this minus sign right here.1121

So, division inside of the logarithm becomes subtraction outside of the logarithm, once we split it into two logs.1133

So, it seems like a lot of rules, and there are a fair bit of new things that you have to get used to here.1141

But they are all based off of our original definition of what it means to be a log--the idea that loga(x) = y means that ay = x.1145

This is really what it is: you can either write it in exponential form or logarithmic form.1153

It is just a way of denoting things.1157

So, a underneath that y, ay, becomes what we were originally taking the log of.1158

And so, for any base a, we also figured out this key idea that for any base a, and any positive number x,1165

there was a b that allowed us to get to that x: ab = x, for any x that we wanted to get to.1171

So, these two ideas--you can put them together, and you can figure out pretty much any one of these things right here with those ideas.1177

And then, these ones are all just coming off of the basic definition, right from the beginning.1186

But if you take that key idea, as well, you can figure these out.1192

So, if you ever forget them on a test, in a situation where you can't just look them up,1194

you now have a way of hopefully being able to figure them out on your own.1197

They are not quite as easy as being able to figure out all of the things that made up our exponential rules,1200

our rules for exponentiation, but we are able to figure these things out on our own.1204

And as you get more used to working with them, and get some practice in them,1209

it will be even easier for you to work them out on your own.1212

And they will also just stick in your head that much easier.1214

All right, now we are going to switch to a new idea.1217

In the last lesson, we mentioned that most calculators only have buttons to evaluate natural log of x and log(x),1220

ln(x) and log(x), that is log base e (that is what natural log means) and log without a number (means base 10).1225

So, how could we evaluate something like log7(42)?1234

Well, 7 to the 1 equals 7, and 7 squared equals 49; so we see that there is no easy integer number that we raise 7 to, to get 42.1237

It is not going to be an easy thing, so we need to use a calculator, because 42 is not an integer power of 7.1248

But since it is base 7, we don't have a button on our calculators.1254

What we want is some way to transform the base of the logarithm.1257

If we could transform from log base 7 into log base 10 or log base e, we would be able to use a calculator,1260

because then we have our natural log and common log buttons on our calculator; we can just punch it in.1266

Now, you might have a calculator that lets you just put in an expression like this.1271

But even if you have that sort of calculator, this is still sort of a useful thing to learn.1275

As we will see in some of the examples, there are ways to apply changes of base beyond just using them to get what these numbers are.1279

And also, lots of times, you won't have a calculator that is able to do this, and you will only have natural log or plain common log, log base 10.1285

And you will need to be able to have this change of base, so that you can change when you need to take a base that isn't e or 10.1293

To help motivate the coming formula and its derivation, let's look at a specific example.1300

Consider the expressions log3(81) and log9(81).1304

log3(81): well, we could rewrite 81 as 34, so we see that that is just 4 over here.1308

Now, log9(81) we could rewrite, also, as 92; so with a base 9, that would come out as 2.1315

So, we see that log3(81) = 2log9(81), because 4 is equal to 2 times 2.1323

So, we see that log3(81) is equal to 2 times log9(81).1333

And this is somehow related to the fact that 32 is equal to 9.1341

You square 3, and you manage to get a 9 out of it.1345

Now, we can probably intuitively know that that holds, generally.1348

We can figure out that normally (or in fact, always), we are going to have log3(x) = 2log9(x).1350

But let's prove it, instead of just assuming--instead of getting a feel that that makes sense, let's actually prove definitely that that is the case.1358

We start by noting that x is equal to 9 to the log9(x).1365

Remember: if we wanted to, we could cancel those things out, because we have a base of 9 and log base 0.1369

So, they would cancel out, and we would end up having just x; so this here makes sense.1378

But having it, 9 to the log9(x), written in this funny way, is a complicated idea.1382

It is hard to see where we pulled it; it is kind of like just pulling a rabbit out of a hat.1386

But with this idea, if we leave it in this form, we will be able to do some cool tricks that will let us show what we want to get to.1390

If we want, we can take log3 of both sides.1396

We know that x is equal to 9log9(x), so it must be the case that log3(x) is the same thing as 9log9(x).1398

So, log3(9log9(x)).1410

We can take log base 3 of both of the things on either side, because that equals sign means that it has to be equal for whatever happens to it.1413

So, log3(x) is equal to log3(9log9(x)).1419

OK; with that idea in mind, we can start applying our rules that we have.1423

We know that we can bring down exponents; so in this case, we have effectively an exponent of log9(x).1427

We actually have it exactly as an exponent, so if we want, we can bring that down in front.1433

We see that log3(x) is equal to log9(x) times log3(9).1437

Now, what is log3(9)? That comes out to be 2, so we can simplify that as log3(x) = 2log9(x).1442

And we have proven what we originally wanted to show.1452

We follow a similar structure to create a formula to change between any two bases, u and v.1456

If we start as x = vlogv(x), which we know is true, because of inverses,1460

then we can once again take a log on both sides; and we will take logu, because we want to get v and u.1465

We want to get both of those logs into action, so we take logu on both sides.1471

And then, we can bring this down in front, because it is an exponent; and we have logu(x) = logv(x) times logu(v).1475

At this point, we can create a formula that will have logv on one side and logu on the other side.1483

We divide logu(v) over, and we rearrange; we swap the order of the equation.1488

We have logv(x) = logu(x)/logu(v).1493

Notice that this allows us to change from an expression logv(x) into an expression that only uses log base u.1503

Now, if we choose our u to be either e or 10 or whatever is convenient for the problem we are working on,1510

we will be able to evaluate it with any calculator at all.1515

Since every calculator we will be using has natural log and common log (base 10 log) buttons,1518

we will be able to evaluate with any calculator, because we will be able to change the u's over here.1523

So, whatever we end up having--if it is log7(42), then we can change it into log10(42)/log10(42).1528

Or alternatively, we could have changed it into ln(42)/ln(42).1538

Both would end up giving the same thing; and we will see what that is in the examples.1544

All right, the first one: Write as a sum and/or difference of logarithms.1549

Our first example here: we are working with base 5, but that doesn't affect how any of our properties work.1552

So, remember: if we have log(M/N), for any base a, then that is equal to loga(M) - loga(N).1558

The same log base is on both, and it splits into subtraction.1570

So, in this case, we have, on the top, x5; so we will have log5, the same thing,1573

minus what is on the bottom, y√z, so - log5(y√z).1580

Great; now, we also have the rule that loga, for any a of M times N, equals loga(M) + loga(N).1596

So, we can split with addition, as well; so we have multiplication here.1609

y times √z is what is really there.1613

log5(x5) -...now, notice: we are splitting all of this here.1617

We are still subtracting by all of it, so we want to put parentheses around it, because it is substitution that we are doing here.1625

So, we now work on this thing here, loga(M) - loga(N).1632

So, our M is y; our N is √z; and we have log...still the same base...of y + log, still the same base (5), of √z.1637

Simplify this out a bit: we have log5(x5) - our subtraction distributes...minus here, as well... log5(√z).1648

Now, that is technically enough, because we have a sum and/or difference of logarithms.1662

But we can also take it one step further, and we can get rid of these exponents.1665

We can get rid of "to the fifth"; we can get rid of √z, because we also have the rule that loga,1668

for any base, of xn, is equal to n times loga(x).1674

So, in this case, we have to the fifth; and how can we rewrite √z?1682

Well, remember: any square root is just like raising to the half, so we can see this:1686

bring the 5 to the front, so we have 5log5(x).1695

We continue to just bring down our log5(y) -...we will rewrite the z...log5(z1/2).1701

And now, we can bring down this, as well...not to there, but we have to move it all the way to the front of the log.1711

There we go: we have 5log5(x) - log5(y) - 1/2log5(z).1718

And there we go: we have managed to write this entirely using very simple things inside of our log: just x, y, and z.1732

We have managed to break up this fairly complicated expression inside of the log into a fairly simple expression1739

inside of the log by just breaking it up into more arithmetic.1745

We can do the reverse, and we can also compact things: write the expression as a single logarithm.1749

We will compact all of these log expressions into one tiny log with a more complicated structure on the inside.1753

So, first, we have, once again, that subtraction becomes division: so 1/3ln(a) + 2...1761

actually, the first thing: we have these coefficients out front.1769

We can also bring the coefficients in, so 1/3 can hop up onto an exponent on that a.1774

The 2 here can hop up to an exponent on that b, so we have ln(a3) + 2(ln(b2)) - ln(c).1780

If you forgot, remember: natural log, ln, is just a way of saying log base e, where e is a special number, the natural base.1794

ln(a1/3) + 2(ln(b2)) - ln(c).1801

Now, we can compact what is inside of those parentheses, because we see we have subtraction.1805

So, that is natural log of b2/c; subtraction of logs is the same thing as division inside of the logarithm.1812

And now, natural log a1/3 plus...well, now we have this 2, so we can take this 2,1821

and it is hitting a log; it is times a log, so it can go up and also become an exponent.1829

So, ln(b2/c)...make sure we remember that we are doing the whole logarithm of that whole thing,1834

so ln(a1/3) + ln...we distribute that...(b4/c2).1844

And we can also bring this in now: natural log of...addition of logarithms becomes multiplication inside of the logarithms.1853

So, a1/3 times the rest of it...b4...it will show up in the numerator, divided by c2.1860

And we have the whole thing compacted into a single logarithm; great.1868

All right, the next one: Evaluate each of the following; use a calculator and the change of base formula.1873

Remember our change of base formula: if we have log7(42), then we can change to any base...1880

I'll put it as a square right now...of 42; the thing that we are taking our log of initially, divided by...1888

the base has to be the same between here and here; these have to be the same base.1899

And it is going to be of our original base; so since it was log7(42), we now have log of something (42), divided by log of something (7).1905

All right, that is how it works: that is what it meant when we saw logv(x) = logu(x)/logu(v).1915

In this case, for this one, our v is 7; our u is whatever we are about to choose.1927

So, we can make it any u we want; we can make it 50, and it would work.1935

We could make it .1, and it would work; but let's do something that shows up on our calculators.1938

So, let's choose e: we can put in an e here and an e here.1942

So, we will rewrite that as ln(42)/ln(7); we punch that into our calculator, and that will end up coming out to be...1948

it will go on with lots of decimals, so let's cut it off, and it will end up being approximately 1.9208.1957

Now, if you wanted to, you could have also done this as something else.1965

It would have also been the same as log10(42)/log10(7).1968

That would be the same if you used common log, something that also shows up on a lot of calculators.1976

And you would end up getting the same thing; it would come out to be approximately 1.9208.1981

Now, if we want to check our work--we want to make sure that that did work out--1986

we would check it by saying that 71.9208 does come out to being 42.1990

And it does come out to being approximately 42, so it ends up checking out if we punch that into a calculator.1998

Let's do logπ(√17); it is the same basic idea here.2004

We can do it as ln(√17)/ln(π); we punch that out in a calculator, and we get approximately equal to 1.2375.2007

And if we wanted to, we also could have done that as log10(√17)/log10(π).2022

And we would have ended up getting the exact same thing.2029

It would have come out to be approximately 1.2375.2032

Either one you work with--they are both going to end up working out to give you the same answer.2034

Great; and if you wanted to, you could also check this, as well.2038

You could check and make sure that π raised to approximately 1.2375 does come out to be approximately √17.2041

And indeed it does, if you want to check that this does work.2049

Great; the fourth example: Given that log5(a) = 6, and log5(b) = 1.2, evaluate each of the following.2053

At this point, we want to use the rules that we have to split things apart.2061

Splitting it apart will allow us to use the pieces of information we have.2064

We have to see a log5(a) before we can swap it out for 6; so we have to get that sort of thing to show up--the same for log5(b).2068

So, we split things up; we have multiplication between each one of these--that is what it means when they are just stacked on top of each other.2075

So, log5(5) + log5(a) + log5(b3):2084

log5(5) is just 1, because it is the same thing as its base, and what it is operating on,2095

plus log5(a); we were told that was 6, so we get 6;2100

plus...now, log5(b3)...we can't do that yet.2104

We need to get it as just a b inside; but we see that there is an exponent.2107

We can bring that out front; so we have 3log5(b).2112

So now, we can use the fact that it is 1.2: 1 + 6 is 7, plus 3 times 1.2 (is 3.6); 7 + 3.6 becomes 10.6; and there is our answer.2117

Work on the other one: log25(√a); this one is a kind of a problem.2139

We have 25 here, but we were told our base for working with the stuff--the information we were given was log base 5.2144

So, we have to use change of base; now we see a time when you have to use change of base,2149

not just for calculating numbers (if you have a calculator that can do change of base on its own,2153

that doesn't need you to do it, then there is still a use for it for problems like this).2158

Change of base: we have that this log25(√a) is the same thing2162

as log of same base of √a, divided by log of some base of what our original base was, 25.2168

So, what do we want to use there? We probably want to use 5, because that is the thing we have all of our information on.2179

So, 5 and 5 here; log5(√a)...now, √a is not what we have--we have a.2184

Is there another way to write √a that would involve a?2193

Yes, √a is the same thing as a1/2: so we can write that as log5(a1/2).2196

divided by log5(25)...well, we see that that is log5(52),2203

because what number do you have to raise 5 to, to get 25? You have to raise it to 2.2209

So at this point, 1/2log5(a)/2log5(5)...log5(5) is just going to be 1.2213

You swap out; we know that we have 6 up here, so it is 1/2 times 6, divided by 2; 1/2 times 6 is equal to 3, still divided by 2.2226

There we go--cool.2239

All right, the final example: Solve the following equations.2241

We didn't talk about how to solve equations like this very much in detail, because hopefully this idea will make sense.2244

But don't worry; we are going to talk about this in great detail in the next lesson, where we will really get into this.2250

But we are just going to start with some simple ones, just in case you end up having any problems like this already that you are working on.2255

So, solve the following equations: log3(x + 5) = 2.2260

Now, remember: we have that inverse property--we know that a to the loga of "something"2264

ends up being equal to something, because these cancel out.2272

Now, notice: we have an equals sign here, so we know that log3(x + 5) is the same thing as 2.2276

So, we can use either one either way we want to.2282

So, that means that a to the something equals a to the something, if it is the same something.2285

So, why don't we choose 3 as our a? 3 to the stuff is equal to 3 to the stuff, as long as it is the same stuff.2290

Let's put 2 over here and log3(x + 5) over here.2301

32 and 3log3(x + 5): 3 and log3 end up canceling out,2309

and x + 5 just drops down; that equals...there is nothing to cancel on the right side; it is 32;2325

but we know what 32 is: 3 times 3 is 9.2331

x + 5 = 9: we subtract 5 on both sides, and we get x = 4.2333

Great; and if we wanted to, we could check that that does end up working out.2338

Check: we plug in our x = 4, so log3(4 + 5) = 2; does it?2342

log3(4 + 5)--let's see if that ends up coming out to be 2.2352

log3(9): what number do we have to raise 3 to, to get 9?2357

We have to raise it to 2; so it checks out.2361

Great; ex - 8 = 47: to do this one, we remember that loga(ax) = x.2364

A log on an exponent, as long as they are both the same base, also cancels out.2375

So, what is the base for e? it is natural log, ln; we could also do loge, but normally it is done as ln.2381

We can take the natural log of both sides; just as we had 3 to the something equals 3 to the something,2388

the natural log of something equals the natural log of something, as long as it is the same something.2393

So, ln(stuff) is equal to ln(stuff), as long as it is the same stuff.2397

Well, we have this right here; so we know that we can plug in 47 over here, and ex - 8 we can plug in over here,2404

because we are guaranteed by that equals sign that it is the same stuff on either side, that they end up being the same thing.2412

So, ln(ex - 8)--well, natural log is just log base e, so these cancel out; and the x - 8 drops down.2417

And that equals ln(47)...well, that is going to end up coming out to be a pretty not-simple number.2425

It is going to have a lot of decimals; so let's just leave it as ln(47) for right now.2431

And we end up getting, by adding 8 to both sides, ln(47) + 8.2435

Now, alternatively, we could also figure out what this is as a decimal approximation.2446

So, if we punch ln(47) into our calculator, and then add 8 to it, we get approximately 11.85.2450

That would also be approximately 11.85.2459

It is precisely ln(47) + 8, but if we want to take ln(47) and have a number that we can work with, it ends up coming out to something with a lot of decimals.2461

It is just like when you have 2 times π you can leave the answer precisely as 2π.2470

But if you want to, you can also approximate that into 6.28...and there is more stuff to it.2477

So, 2 times π is the exact answer; but you also might want a decimal answer to work with, so you can approximate it by multiplying it out.2485

The natural log of 47 is the same sort of thing as in the π example.2491

It is something that is a complicated number, so we might want to leave it precisely, or we might want to get it approximately.2495

We can check with this number; and we have that e to the...let's use our decimal approximation,2500

so we can actually put it into a calculator...11.85, minus 8...what do we put that in?2505

That will become e3.85; e3.85 ends up being approximately 46.99.2511

So, that ends up checking out, because ultimately, remember, we just said it was an approximation, not perfectly the answer.2520

The thing that is perfectly the answer is this one right here.2526

This is pretty great stuff that allows us to get a whole bunch of applications worked out with this,2529

as we will see two lessons from now, when we talk about applications of the stuff.2532

And in the next lesson, we will really dive into how we solve equations like this.2536

So, if you want more information on that, check out the next lesson,2540

where we will really see some really complicated examples, and get a really great idea of how these things work.2543

And we will really understand how to solve all of these sorts of equations.2548

All right, we will see you at Educator.com later--goodbye!2551