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INSTRUCTORS Raffi Hovasapian John Zhu
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Raffi Hovasapian

Raffi Hovasapian

The Definite Integral

Slide Duration:

Table of Contents

I. Limits and Derivatives
Overview & Slopes of Curves

42m 8s

Intro
0:00
Overview & Slopes of Curves
0:21
Differential and Integral
0:22
Fundamental Theorem of Calculus
6:36
Differentiation or Taking the Derivative
14:24
What Does the Derivative Mean and How do We Find it?
15:18
Example: f'(x)
19:24
Example: f(x) = sin (x)
29:16
General Procedure for Finding the Derivative of f(x)
37:33
More on Slopes of Curves

50m 53s

Intro
0:00
Slope of the Secant Line along a Curve
0:12
Slope of the Tangent Line to f(x) at a Particlar Point
0:13
Slope of the Secant Line along a Curve
2:59
Instantaneous Slope
6:51
Instantaneous Slope
6:52
Example: Distance, Time, Velocity
13:32
Instantaneous Slope and Average Slope
25:42
Slope & Rate of Change
29:55
Slope & Rate of Change
29:56
Example: Slope = 2
33:16
Example: Slope = 4/3
34:32
Example: Slope = 4 (m/s)
39:12
Example: Density = Mass / Volume
40:33
Average Slope, Average Rate of Change, Instantaneous Slope, and Instantaneous Rate of Change
47:46
Example Problems for Slopes of Curves

59m 12s

Intro
0:00
Example I: Water Tank
0:13
Part A: Which is the Independent Variable and Which is the Dependent?
2:00
Part B: Average Slope
3:18
Part C: Express These Slopes as Rates-of-Change
9:28
Part D: Instantaneous Slope
14:54
Example II: y = √(x-3)
28:26
Part A: Calculate the Slope of the Secant Line
30:39
Part B: Instantaneous Slope
41:26
Part C: Equation for the Tangent Line
43:59
Example III: Object in the Air
49:37
Part A: Average Velocity
50:37
Part B: Instantaneous Velocity
55:30
Desmos Tutorial

18m 43s

Intro
0:00
Desmos Tutorial
1:42
Desmos Tutorial
1:43
Things You Must Learn To Do on Your Particular Calculator
2:39
Things You Must Learn To Do on Your Particular Calculator
2:40
Example I: y=sin x
4:54
Example II: y=x³ and y = d/(dx) (x³)
9:22
Example III: y = x² {-5 <= x <= 0} and y = cos x {0 < x < 6}
13:15
The Limit of a Function

51m 53s

Intro
0:00
The Limit of a Function
0:14
The Limit of a Function
0:15
Graph: Limit of a Function
12:24
Table of Values
16:02
lim x→a f(x) Does not Say What Happens When x = a
20:05
Example I: f(x) = x²
24:34
Example II: f(x) = 7
27:05
Example III: f(x) = 4.5
30:33
Example IV: f(x) = 1/x
34:03
Example V: f(x) = 1/x²
36:43
The Limit of a Function, Cont.
38:16
Infinity and Negative Infinity
38:17
Does Not Exist
42:45
Summary
46:48
Example Problems for the Limit of a Function

24m 43s

Intro
0:00
Example I: Explain in Words What the Following Symbols Mean
0:10
Example II: Find the Following Limit
5:21
Example III: Use the Graph to Find the Following Limits
7:35
Example IV: Use the Graph to Find the Following Limits
11:48
Example V: Sketch the Graph of a Function that Satisfies the Following Properties
15:25
Example VI: Find the Following Limit
18:44
Example VII: Find the Following Limit
20:06
Calculating Limits Mathematically

53m 48s

Intro
0:00
Plug-in Procedure
0:09
Plug-in Procedure
0:10
Limit Laws
9:14
Limit Law 1
10:05
Limit Law 2
10:54
Limit Law 3
11:28
Limit Law 4
11:54
Limit Law 5
12:24
Limit Law 6
13:14
Limit Law 7
14:38
Plug-in Procedure, Cont.
16:35
Plug-in Procedure, Cont.
16:36
Example I: Calculating Limits Mathematically
20:50
Example II: Calculating Limits Mathematically
27:37
Example III: Calculating Limits Mathematically
31:42
Example IV: Calculating Limits Mathematically
35:36
Example V: Calculating Limits Mathematically
40:58
Limits Theorem
44:45
Limits Theorem 1
44:46
Limits Theorem 2: Squeeze Theorem
46:34
Example VI: Calculating Limits Mathematically
49:26
Example Problems for Calculating Limits Mathematically

21m 22s

Intro
0:00
Example I: Evaluate the Following Limit by Showing Each Application of a Limit Law
0:16
Example II: Evaluate the Following Limit
1:51
Example III: Evaluate the Following Limit
3:36
Example IV: Evaluate the Following Limit
8:56
Example V: Evaluate the Following Limit
11:19
Example VI: Calculating Limits Mathematically
13:19
Example VII: Calculating Limits Mathematically
14:59
Calculating Limits as x Goes to Infinity

50m 1s

Intro
0:00
Limit as x Goes to Infinity
0:14
Limit as x Goes to Infinity
0:15
Let's Look at f(x) = 1 / (x-3)
1:04
Summary
9:34
Example I: Calculating Limits as x Goes to Infinity
12:16
Example II: Calculating Limits as x Goes to Infinity
21:22
Example III: Calculating Limits as x Goes to Infinity
24:10
Example IV: Calculating Limits as x Goes to Infinity
36:00
Example Problems for Limits at Infinity

36m 31s

Intro
0:00
Example I: Calculating Limits as x Goes to Infinity
0:14
Example II: Calculating Limits as x Goes to Infinity
3:27
Example III: Calculating Limits as x Goes to Infinity
8:11
Example IV: Calculating Limits as x Goes to Infinity
14:20
Example V: Calculating Limits as x Goes to Infinity
20:07
Example VI: Calculating Limits as x Goes to Infinity
23:36
Continuity

53m

Intro
0:00
Definition of Continuity
0:08
Definition of Continuity
0:09
Example: Not Continuous
3:52
Example: Continuous
4:58
Example: Not Continuous
5:52
Procedure for Finding Continuity
9:45
Law of Continuity
13:44
Law of Continuity
13:45
Example I: Determining Continuity on a Graph
15:55
Example II: Show Continuity & Determine the Interval Over Which the Function is Continuous
17:57
Example III: Is the Following Function Continuous at the Given Point?
22:42
Theorem for Composite Functions
25:28
Theorem for Composite Functions
25:29
Example IV: Is cos(x³ + ln x) Continuous at x=π/2?
27:00
Example V: What Value of A Will make the Following Function Continuous at Every Point of Its Domain?
34:04
Types of Discontinuity
39:18
Removable Discontinuity
39:33
Jump Discontinuity
40:06
Infinite Discontinuity
40:32
Intermediate Value Theorem
40:58
Intermediate Value Theorem: Hypothesis & Conclusion
40:59
Intermediate Value Theorem: Graphically
43:40
Example VI: Prove That the Following Function Has at Least One Real Root in the Interval [4,6]
47:46
Derivative I

40m 2s

Intro
0:00
Derivative
0:09
Derivative
0:10
Example I: Find the Derivative of f(x)=x³
2:20
Notations for the Derivative
7:32
Notations for the Derivative
7:33
Derivative & Rate of Change
11:14
Recall the Rate of Change
11:15
Instantaneous Rate of Change
17:04
Graphing f(x) and f'(x)
19:10
Example II: Find the Derivative of x⁴ - x²
24:00
Example III: Find the Derivative of f(x)=√x
30:51
Derivatives II

53m 45s

Intro
0:00
Example I: Find the Derivative of (2+x)/(3-x)
0:18
Derivatives II
9:02
f(x) is Differentiable if f'(x) Exists
9:03
Recall: For a Limit to Exist, Both Left Hand and Right Hand Limits Must Equal to Each Other
17:19
Geometrically: Differentiability Means the Graph is Smooth
18:44
Example II: Show Analytically that f(x) = |x| is Nor Differentiable at x=0
20:53
Example II: For x > 0
23:53
Example II: For x < 0
25:36
Example II: What is f(0) and What is the lim |x| as x→0?
30:46
Differentiability & Continuity
34:22
Differentiability & Continuity
34:23
How Can a Function Not be Differentiable at a Point?
39:38
How Can a Function Not be Differentiable at a Point?
39:39
Higher Derivatives
41:58
Higher Derivatives
41:59
Derivative Operator
45:12
Example III: Find (dy)/(dx) & (d²y)/(dx²) for y = x³
49:29
More Example Problems for The Derivative

31m 38s

Intro
0:00
Example I: Sketch f'(x)
0:10
Example II: Sketch f'(x)
2:14
Example III: Find the Derivative of the Following Function sing the Definition
3:49
Example IV: Determine f, f', and f'' on a Graph
12:43
Example V: Find an Equation for the Tangent Line to the Graph of the Following Function at the Given x-value
13:40
Example VI: Distance vs. Time
20:15
Example VII: Displacement, Velocity, and Acceleration
23:56
Example VIII: Graph the Displacement Function
28:20
II. Differentiation
Differentiation of Polynomials & Exponential Functions

47m 35s

Intro
0:00
Differentiation of Polynomials & Exponential Functions
0:15
Derivative of a Function
0:16
Derivative of a Constant
2:35
Power Rule
3:08
If C is a Constant
4:19
Sum Rule
5:22
Exponential Functions
6:26
Example I: Differentiate
7:45
Example II: Differentiate
12:38
Example III: Differentiate
15:13
Example IV: Differentiate
16:20
Example V: Differentiate
19:19
Example VI: Find the Equation of the Tangent Line to a Function at a Given Point
12:18
Example VII: Find the First & Second Derivatives
25:59
Example VIII
27:47
Part A: Find the Velocity & Acceleration Functions as Functions of t
27:48
Part B: Find the Acceleration after 3 Seconds
30:12
Part C: Find the Acceleration when the Velocity is 0
30:53
Part D: Graph the Position, Velocity, & Acceleration Graphs
32:50
Example IX: Find a Cubic Function Whose Graph has Horizontal Tangents
34:53
Example X: Find a Point on a Graph
42:31
The Product, Power & Quotient Rules

47m 25s

Intro
0:00
The Product, Power and Quotient Rules
0:19
Differentiate Functions
0:20
Product Rule
5:30
Quotient Rule
9:15
Power Rule
10:00
Example I: Product Rule
13:48
Example II: Quotient Rule
16:13
Example III: Power Rule
18:28
Example IV: Find dy/dx
19:57
Example V: Find dy/dx
24:53
Example VI: Find dy/dx
28:38
Example VII: Find an Equation for the Tangent to the Curve
34:54
Example VIII: Find d²y/dx²
38:08
Derivatives of the Trigonometric Functions

41m 8s

Intro
0:00
Derivatives of the Trigonometric Functions
0:09
Let's Find the Derivative of f(x) = sin x
0:10
Important Limits to Know
4:59
d/dx (sin x)
6:06
d/dx (cos x)
6:38
d/dx (tan x)
6:50
d/dx (csc x)
7:02
d/dx (sec x)
7:15
d/dx (cot x)
7:27
Example I: Differentiate f(x) = x² - 4 cos x
7:56
Example II: Differentiate f(x) = x⁵ tan x
9:04
Example III: Differentiate f(x) = (cos x) / (3 + sin x)
10:56
Example IV: Differentiate f(x) = e^x / (tan x - sec x)
14:06
Example V: Differentiate f(x) = (csc x - 4) / (cot x)
15:37
Example VI: Find an Equation of the Tangent Line
21:48
Example VII: For What Values of x Does the Graph of the Function x + 3 cos x Have a Horizontal Tangent?
25:17
Example VIII: Ladder Problem
28:23
Example IX: Evaluate
33:22
Example X: Evaluate
36:38
The Chain Rule

24m 56s

Intro
0:00
The Chain Rule
0:13
Recall the Composite Functions
0:14
Derivatives of Composite Functions
1:34
Example I: Identify f(x) and g(x) and Differentiate
6:41
Example II: Identify f(x) and g(x) and Differentiate
9:47
Example III: Differentiate
11:03
Example IV: Differentiate f(x) = -5 / (x² + 3)³
12:15
Example V: Differentiate f(x) = cos(x² + c²)
14:35
Example VI: Differentiate f(x) = cos⁴x +c²
15:41
Example VII: Differentiate
17:03
Example VIII: Differentiate f(x) = sin(tan x²)
19:01
Example IX: Differentiate f(x) = sin(tan² x)
21:02
More Chain Rule Example Problems

25m 32s

Intro
0:00
Example I: Differentiate f(x) = sin(cos(tanx))
0:38
Example II: Find an Equation for the Line Tangent to the Given Curve at the Given Point
2:25
Example III: F(x) = f(g(x)), Find F' (6)
4:22
Example IV: Differentiate & Graph both the Function & the Derivative in the Same Window
5:35
Example V: Differentiate f(x) = ( (x-8)/(x+3) )⁴
10:18
Example VI: Differentiate f(x) = sec²(12x)
12:28
Example VII: Differentiate
14:41
Example VIII: Differentiate
19:25
Example IX: Find an Expression for the Rate of Change of the Volume of the Balloon with Respect to Time
21:13
Implicit Differentiation

52m 31s

Intro
0:00
Implicit Differentiation
0:09
Implicit Differentiation
0:10
Example I: Find (dy)/(dx) by both Implicit Differentiation and Solving Explicitly for y
12:15
Example II: Find (dy)/(dx) of x³ + x²y + 7y² = 14
19:18
Example III: Find (dy)/(dx) of x³y² + y³x² = 4x
21:43
Example IV: Find (dy)/(dx) of the Following Equation
24:13
Example V: Find (dy)/(dx) of 6sin x cos y = 1
29:00
Example VI: Find (dy)/(dx) of x² cos² y + y sin x = 2sin x cos y
31:02
Example VII: Find (dy)/(dx) of √(xy) = 7 + y²e^x
37:36
Example VIII: Find (dy)/(dx) of 4(x²+y²)² = 35(x²-y²)
41:03
Example IX: Find (d²y)/(dx²) of x² + y² = 25
44:05
Example X: Find (d²y)/(dx²) of sin x + cos y = sin(2x)
47:48
III. Applications of the Derivative
Linear Approximations & Differentials

47m 34s

Intro
0:00
Linear Approximations & Differentials
0:09
Linear Approximations & Differentials
0:10
Example I: Linear Approximations & Differentials
11:27
Example II: Linear Approximations & Differentials
20:19
Differentials
30:32
Differentials
30:33
Example III: Linear Approximations & Differentials
34:09
Example IV: Linear Approximations & Differentials
35:57
Example V: Relative Error
38:46
Related Rates

45m 33s

Intro
0:00
Related Rates
0:08
Strategy for Solving Related Rates Problems #1
0:09
Strategy for Solving Related Rates Problems #2
1:46
Strategy for Solving Related Rates Problems #3
2:06
Strategy for Solving Related Rates Problems #4
2:50
Strategy for Solving Related Rates Problems #5
3:38
Example I: Radius of a Balloon
5:15
Example II: Ladder
12:52
Example III: Water Tank
19:08
Example IV: Distance between Two Cars
29:27
Example V: Line-of-Sight
36:20
More Related Rates Examples

37m 17s

Intro
0:00
Example I: Shadow
0:14
Example II: Particle
4:45
Example III: Water Level
10:28
Example IV: Clock
20:47
Example V: Distance between a House and a Plane
29:11
Maximum & Minimum Values of a Function

40m 44s

Intro
0:00
Maximum & Minimum Values of a Function, Part 1
0:23
Absolute Maximum
2:20
Absolute Minimum
2:52
Local Maximum
3:38
Local Minimum
4:26
Maximum & Minimum Values of a Function, Part 2
6:11
Function with Absolute Minimum but No Absolute Max, Local Max, and Local Min
7:18
Function with Local Max & Min but No Absolute Max & Min
8:48
Formal Definitions
10:43
Absolute Maximum
11:18
Absolute Minimum
12:57
Local Maximum
14:37
Local Minimum
16:25
Extreme Value Theorem
18:08
Theorem: f'(c) = 0
24:40
Critical Number (Critical Value)
26:14
Procedure for Finding the Critical Values of f(x)
28:32
Example I: Find the Critical Values of f(x) x + sinx
29:51
Example II: What are the Absolute Max & Absolute Minimum of f(x) = x + 4 sinx on [0,2π]
35:31
Example Problems for Max & Min

40m 44s

Intro
0:00
Example I: Identify Absolute and Local Max & Min on the Following Graph
0:11
Example II: Sketch the Graph of a Continuous Function
3:11
Example III: Sketch the Following Graphs
4:40
Example IV: Find the Critical Values of f (x) = 3x⁴ - 7x³ + 4x²
6:13
Example V: Find the Critical Values of f(x) = |2x - 5|
8:42
Example VI: Find the Critical Values
11:42
Example VII: Find the Critical Values f(x) = cos²(2x) on [0,2π]
16:57
Example VIII: Find the Absolute Max & Min f(x) = 2sinx + 2cos x on [0,(π/3)]
20:08
Example IX: Find the Absolute Max & Min f(x) = (ln(2x)) / x on [1,3]
24:39
The Mean Value Theorem

25m 54s

Intro
0:00
Rolle's Theorem
0:08
Rolle's Theorem: If & Then
0:09
Rolle's Theorem: Geometrically
2:06
There May Be More than 1 c Such That f'( c ) = 0
3:30
Example I: Rolle's Theorem
4:58
The Mean Value Theorem
9:12
The Mean Value Theorem: If & Then
9:13
The Mean Value Theorem: Geometrically
11:07
Example II: Mean Value Theorem
13:43
Example III: Mean Value Theorem
21:19
Using Derivatives to Graph Functions, Part I

25m 54s

Intro
0:00
Using Derivatives to Graph Functions, Part I
0:12
Increasing/ Decreasing Test
0:13
Example I: Find the Intervals Over Which the Function is Increasing & Decreasing
3:26
Example II: Find the Local Maxima & Minima of the Function
19:18
Example III: Find the Local Maxima & Minima of the Function
31:39
Using Derivatives to Graph Functions, Part II

44m 58s

Intro
0:00
Using Derivatives to Graph Functions, Part II
0:13
Concave Up & Concave Down
0:14
What Does This Mean in Terms of the Derivative?
6:14
Point of Inflection
8:52
Example I: Graph the Function
13:18
Example II: Function x⁴ - 5x²
19:03
Intervals of Increase & Decrease
19:04
Local Maxes and Mins
25:01
Intervals of Concavity & X-Values for the Points of Inflection
29:18
Intervals of Concavity & Y-Values for the Points of Inflection
34:18
Graphing the Function
40:52
Example Problems I

49m 19s

Intro
0:00
Example I: Intervals, Local Maxes & Mins
0:26
Example II: Intervals, Local Maxes & Mins
5:05
Example III: Intervals, Local Maxes & Mins, and Inflection Points
13:40
Example IV: Intervals, Local Maxes & Mins, Inflection Points, and Intervals of Concavity
23:02
Example V: Intervals, Local Maxes & Mins, Inflection Points, and Intervals of Concavity
34:36
Example Problems III

59m 1s

Intro
0:00
Example I: Intervals, Local Maxes & Mins, Inflection Points, Intervals of Concavity, and Asymptotes
0:11
Example II: Intervals, Local Maxes & Mins, Inflection Points, Intervals of Concavity, and Asymptotes
21:24
Example III: Cubic Equation f(x) = Ax³ + Bx² + Cx + D
37:56
Example IV: Intervals, Local Maxes & Mins, Inflection Points, Intervals of Concavity, and Asymptotes
46:19
L'Hospital's Rule

30m 9s

Intro
0:00
L'Hospital's Rule
0:19
Indeterminate Forms
0:20
L'Hospital's Rule
3:38
Example I: Evaluate the Following Limit Using L'Hospital's Rule
8:50
Example II: Evaluate the Following Limit Using L'Hospital's Rule
10:30
Indeterminate Products
11:54
Indeterminate Products
11:55
Example III: L'Hospital's Rule & Indeterminate Products
13:57
Indeterminate Differences
17:00
Indeterminate Differences
17:01
Example IV: L'Hospital's Rule & Indeterminate Differences
18:57
Indeterminate Powers
22:20
Indeterminate Powers
22:21
Example V: L'Hospital's Rule & Indeterminate Powers
25:13
Example Problems for L'Hospital's Rule

38m 14s

Intro
0:00
Example I: Evaluate the Following Limit
0:17
Example II: Evaluate the Following Limit
2:45
Example III: Evaluate the Following Limit
6:54
Example IV: Evaluate the Following Limit
8:43
Example V: Evaluate the Following Limit
11:01
Example VI: Evaluate the Following Limit
14:48
Example VII: Evaluate the Following Limit
17:49
Example VIII: Evaluate the Following Limit
20:37
Example IX: Evaluate the Following Limit
25:16
Example X: Evaluate the Following Limit
32:44
Optimization Problems I

49m 59s

Intro
0:00
Example I: Find the Dimensions of the Box that Gives the Greatest Volume
1:23
Fundamentals of Optimization Problems
18:08
Fundamental #1
18:33
Fundamental #2
19:09
Fundamental #3
19:19
Fundamental #4
20:59
Fundamental #5
21:55
Fundamental #6
23:44
Example II: Demonstrate that of All Rectangles with a Given Perimeter, the One with the Largest Area is a Square
24:36
Example III: Find the Points on the Ellipse 9x² + y² = 9 Farthest Away from the Point (1,0)
35:13
Example IV: Find the Dimensions of the Rectangle of Largest Area that can be Inscribed in a Circle of Given Radius R
43:10
Optimization Problems II

55m 10s

Intro
0:00
Example I: Optimization Problem
0:13
Example II: Optimization Problem
17:34
Example III: Optimization Problem
35:06
Example IV: Revenue, Cost, and Profit
43:22
Newton's Method

30m 22s

Intro
0:00
Newton's Method
0:45
Newton's Method
0:46
Example I: Find x2 and x3
13:18
Example II: Use Newton's Method to Approximate
15:48
Example III: Find the Root of the Following Equation to 6 Decimal Places
19:57
Example IV: Use Newton's Method to Find the Coordinates of the Inflection Point
23:11
IV. Integrals
Antiderivatives

55m 26s

Intro
0:00
Antiderivatives
0:23
Definition of an Antiderivative
0:24
Antiderivative Theorem
7:58
Function & Antiderivative
12:10
x^n
12:30
1/x
13:00
e^x
13:08
cos x
13:18
sin x
14:01
sec² x
14:11
secxtanx
14:18
1/√(1-x²)
14:26
1/(1+x²)
14:36
-1/√(1-x²)
14:45
Example I: Find the Most General Antiderivative for the Following Functions
15:07
Function 1: f(x) = x³ -6x² + 11x - 9
15:42
Function 2: f(x) = 14√(x) - 27 4√x
19:12
Function 3: (fx) = cos x - 14 sinx
20:53
Function 4: f(x) = (x⁵+2√x )/( x^(4/3) )
22:10
Function 5: f(x) = (3e^x) - 2/(1+x²)
25:42
Example II: Given the Following, Find the Original Function f(x)
26:37
Function 1: f'(x) = 5x³ - 14x + 24, f(2) = 40
27:55
Function 2: f'(x) 3 sinx + sec²x, f(π/6) = 5
30:34
Function 3: f''(x) = 8x - cos x, f(1.5) = 12.7, f'(1.5) = 4.2
32:54
Function 4: f''(x) = 5/(√x), f(2) 15, f'(2) = 7
37:54
Example III: Falling Object
41:58
Problem 1: Find an Equation for the Height of the Ball after t Seconds
42:48
Problem 2: How Long Will It Take for the Ball to Strike the Ground?
48:30
Problem 3: What is the Velocity of the Ball as it Hits the Ground?
49:52
Problem 4: Initial Velocity of 6 m/s, How Long Does It Take to Reach the Ground?
50:46
The Area Under a Curve

51m 3s

Intro
0:00
The Area Under a Curve
0:13
Approximate Using Rectangles
0:14
Let's Do This Again, Using 4 Different Rectangles
9:40
Approximate with Rectangles
16:10
Left Endpoint
18:08
Right Endpoint
25:34
Left Endpoint vs. Right Endpoint
30:58
Number of Rectangles
34:08
True Area
37:36
True Area
37:37
Sigma Notation & Limits
43:32
When You Have to Explicitly Solve Something
47:56
Example Problems for Area Under a Curve

33m 7s

Intro
0:00
Example I: Using Left Endpoint & Right Endpoint to Approximate Area Under a Curve
0:10
Example II: Using 5 Rectangles, Approximate the Area Under the Curve
11:32
Example III: Find the True Area by Evaluating the Limit Expression
16:07
Example IV: Find the True Area by Evaluating the Limit Expression
24:52
The Definite Integral

43m 19s

Intro
0:00
The Definite Integral
0:08
Definition to Find the Area of a Curve
0:09
Definition of the Definite Integral
4:08
Symbol for Definite Integral
8:45
Regions Below the x-axis
15:18
Associating Definite Integral to a Function
19:38
Integrable Function
27:20
Evaluating the Definite Integral
29:26
Evaluating the Definite Integral
29:27
Properties of the Definite Integral
35:24
Properties of the Definite Integral
35:25
Example Problems for The Definite Integral

32m 14s

Intro
0:00
Example I: Approximate the Following Definite Integral Using Midpoints & Sub-intervals
0:11
Example II: Express the Following Limit as a Definite Integral
5:28
Example III: Evaluate the Following Definite Integral Using the Definition
6:28
Example IV: Evaluate the Following Integral Using the Definition
17:06
Example V: Evaluate the Following Definite Integral by Using Areas
25:41
Example VI: Definite Integral
30:36
The Fundamental Theorem of Calculus

24m 17s

Intro
0:00
The Fundamental Theorem of Calculus
0:17
Evaluating an Integral
0:18
Lim as x → ∞
12:19
Taking the Derivative
14:06
Differentiation & Integration are Inverse Processes
15:04
1st Fundamental Theorem of Calculus
20:08
1st Fundamental Theorem of Calculus
20:09
2nd Fundamental Theorem of Calculus
22:30
2nd Fundamental Theorem of Calculus
22:31
Example Problems for the Fundamental Theorem

25m 21s

Intro
0:00
Example I: Find the Derivative of the Following Function
0:17
Example II: Find the Derivative of the Following Function
1:40
Example III: Find the Derivative of the Following Function
2:32
Example IV: Find the Derivative of the Following Function
5:55
Example V: Evaluate the Following Integral
7:13
Example VI: Evaluate the Following Integral
9:46
Example VII: Evaluate the Following Integral
12:49
Example VIII: Evaluate the Following Integral
13:53
Example IX: Evaluate the Following Graph
15:24
Local Maxs and Mins for g(x)
15:25
Where Does g(x) Achieve Its Absolute Max on [0,8]
20:54
On What Intervals is g(x) Concave Up/Down?
22:20
Sketch a Graph of g(x)
24:34
More Example Problems, Including Net Change Applications

34m 22s

Intro
0:00
Example I: Evaluate the Following Indefinite Integral
0:10
Example II: Evaluate the Following Definite Integral
0:59
Example III: Evaluate the Following Integral
2:59
Example IV: Velocity Function
7:46
Part A: Net Displacement
7:47
Part B: Total Distance Travelled
13:15
Example V: Linear Density Function
20:56
Example VI: Acceleration Function
25:10
Part A: Velocity Function at Time t
25:11
Part B: Total Distance Travelled During the Time Interval
28:38
Solving Integrals by Substitution

27m 20s

Intro
0:00
Table of Integrals
0:35
Example I: Evaluate the Following Indefinite Integral
2:02
Example II: Evaluate the Following Indefinite Integral
7:27
Example IIII: Evaluate the Following Indefinite Integral
10:57
Example IV: Evaluate the Following Indefinite Integral
12:33
Example V: Evaluate the Following
14:28
Example VI: Evaluate the Following
16:00
Example VII: Evaluate the Following
19:01
Example VIII: Evaluate the Following
21:49
Example IX: Evaluate the Following
24:34
V. Applications of Integration
Areas Between Curves

34m 56s

Intro
0:00
Areas Between Two Curves: Function of x
0:08
Graph 1: Area Between f(x) & g(x)
0:09
Graph 2: Area Between f(x) & g(x)
4:07
Is It Possible to Write as a Single Integral?
8:20
Area Between the Curves on [a,b]
9:24
Absolute Value
10:32
Formula for Areas Between Two Curves: Top Function - Bottom Function
17:03
Areas Between Curves: Function of y
17:49
What if We are Given Functions of y?
17:50
Formula for Areas Between Two Curves: Right Function - Left Function
21:48
Finding a & b
22:32
Example Problems for Areas Between Curves

42m 55s

Intro
0:00
Instructions for the Example Problems
0:10
Example I: y = 7x - x² and y=x
0:37
Example II: x=y²-3, x=e^((1/2)y), y=-1, and y=2
6:25
Example III: y=(1/x), y=(1/x³), and x=4
12:25
Example IV: 15-2x² and y=x²-5
15:52
Example V: x=(1/8)y³ and x=6-y²
20:20
Example VI: y=cos x, y=sin(2x), [0,π/2]
24:34
Example VII: y=2x², y=10x², 7x+2y=10
29:51
Example VIII: Velocity vs. Time
33:23
Part A: At 2.187 Minutes, Which care is Further Ahead?
33:24
Part B: If We Shaded the Region between the Graphs from t=0 to t=2.187, What Would This Shaded Area Represent?
36:32
Part C: At 4 Minutes Which Car is Ahead?
37:11
Part D: At What Time Will the Cars be Side by Side?
37:50
Volumes I: Slices

34m 15s

Intro
0:00
Volumes I: Slices
0:18
Rotate the Graph of y=√x about the x-axis
0:19
How can I use Integration to Find the Volume?
3:16
Slice the Solid Like a Loaf of Bread
5:06
Volumes Definition
8:56
Example I: Find the Volume of the Solid Obtained by Rotating the Region Bounded by the Given Functions about the Given Line of Rotation
12:18
Example II: Find the Volume of the Solid Obtained by Rotating the Region Bounded by the Given Functions about the Given Line of Rotation
19:05
Example III: Find the Volume of the Solid Obtained by Rotating the Region Bounded by the Given Functions about the Given Line of Rotation
25:28
Volumes II: Volumes by Washers

51m 43s

Intro
0:00
Volumes II: Volumes by Washers
0:11
Rotating Region Bounded by y=x³ & y=x around the x-axis
0:12
Equation for Volumes by Washer
11:14
Process for Solving Volumes by Washer
13:40
Example I: Find the Volume of the Solid Obtained by Rotating the Region Bounded by the Following Functions around the Given Axis
15:58
Example II: Find the Volume of the Solid Obtained by Rotating the Region Bounded by the Following Functions around the Given Axis
25:07
Example III: Find the Volume of the Solid Obtained by Rotating the Region Bounded by the Following Functions around the Given Axis
34:20
Example IV: Find the Volume of the Solid Obtained by Rotating the Region Bounded by the Following Functions around the Given Axis
44:05
Volumes III: Solids That Are Not Solids-of-Revolution

49m 36s

Intro
0:00
Solids That Are Not Solids-of-Revolution
0:11
Cross-Section Area Review
0:12
Cross-Sections That Are Not Solids-of-Revolution
7:36
Example I: Find the Volume of a Pyramid Whose Base is a Square of Side-length S, and Whose Height is H
10:54
Example II: Find the Volume of a Solid Whose Cross-sectional Areas Perpendicular to the Base are Equilateral Triangles
20:39
Example III: Find the Volume of a Pyramid Whose Base is an Equilateral Triangle of Side-Length A, and Whose Height is H
29:27
Example IV: Find the Volume of a Solid Whose Base is Given by the Equation 16x² + 4y² = 64
36:47
Example V: Find the Volume of a Solid Whose Base is the Region Bounded by the Functions y=3-x² and the x-axis
46:13
Volumes IV: Volumes By Cylindrical Shells

50m 2s

Intro
0:00
Volumes by Cylindrical Shells
0:11
Find the Volume of the Following Region
0:12
Volumes by Cylindrical Shells: Integrating Along x
14:12
Volumes by Cylindrical Shells: Integrating Along y
14:40
Volumes by Cylindrical Shells Formulas
16:22
Example I: Using the Method of Cylindrical Shells, Find the Volume of the Solid
18:33
Example II: Using the Method of Cylindrical Shells, Find the Volume of the Solid
25:57
Example III: Using the Method of Cylindrical Shells, Find the Volume of the Solid
31:38
Example IV: Using the Method of Cylindrical Shells, Find the Volume of the Solid
38:44
Example V: Using the Method of Cylindrical Shells, Find the Volume of the Solid
44:03
The Average Value of a Function

32m 13s

Intro
0:00
The Average Value of a Function
0:07
Average Value of f(x)
0:08
What if The Domain of f(x) is Not Finite?
2:23
Let's Calculate Average Value for f(x) = x² [2,5]
4:46
Mean Value Theorem for Integrate
9:25
Example I: Find the Average Value of the Given Function Over the Given Interval
14:06
Example II: Find the Average Value of the Given Function Over the Given Interval
18:25
Example III: Find the Number A Such that the Average Value of the Function f(x) = -4x² + 8x + 4 Equals 2 Over the Interval [-1,A]
24:04
Example IV: Find the Average Density of a Rod
27:47
VI. Techniques of Integration
Integration by Parts

50m 32s

Intro
0:00
Integration by Parts
0:08
The Product Rule for Differentiation
0:09
Integrating Both Sides Retains the Equality
0:52
Differential Notation
2:24
Example I: ∫ x cos x dx
5:41
Example II: ∫ x² sin(2x)dx
12:01
Example III: ∫ (e^x) cos x dx
18:19
Example IV: ∫ (sin^-1) (x) dx
23:42
Example V: ∫₁⁵ (lnx)² dx
28:25
Summary
32:31
Tabular Integration
35:08
Case 1
35:52
Example: ∫x³sinx dx
36:39
Case 2
40:28
Example: ∫e^(2x) sin 3x
41:14
Trigonometric Integrals I

24m 50s

Intro
0:00
Example I: ∫ sin³ (x) dx
1:36
Example II: ∫ cos⁵(x)sin²(x)dx
4:36
Example III: ∫ sin⁴(x)dx
9:23
Summary for Evaluating Trigonometric Integrals of the Following Type: ∫ (sin^m) (x) (cos^p) (x) dx
15:59
#1: Power of sin is Odd
16:00
#2: Power of cos is Odd
16:41
#3: Powers of Both sin and cos are Odd
16:55
#4: Powers of Both sin and cos are Even
17:10
Example IV: ∫ tan⁴ (x) sec⁴ (x) dx
17:34
Example V: ∫ sec⁹(x) tan³(x) dx
20:55
Summary for Evaluating Trigonometric Integrals of the Following Type: ∫ (sec^m) (x) (tan^p) (x) dx
23:31
#1: Power of sec is Odd
23:32
#2: Power of tan is Odd
24:04
#3: Powers of sec is Odd and/or Power of tan is Even
24:18
Trigonometric Integrals II

22m 12s

Intro
0:00
Trigonometric Integrals II
0:09
Recall: ∫tanx dx
0:10
Let's Find ∫secx dx
3:23
Example I: ∫ tan⁵ (x) dx
6:23
Example II: ∫ sec⁵ (x) dx
11:41
Summary: How to Deal with Integrals of Different Types
19:04
Identities to Deal with Integrals of Different Types
19:05
Example III: ∫cos(5x)sin(9x)dx
19:57
More Example Problems for Trigonometric Integrals

17m 22s

Intro
0:00
Example I: ∫sin²(x)cos⁷(x)dx
0:14
Example II: ∫x sin²(x) dx
3:56
Example III: ∫csc⁴ (x/5)dx
8:39
Example IV: ∫( (1-tan²x)/(sec²x) ) dx
11:17
Example V: ∫ 1 / (sinx-1) dx
13:19
Integration by Partial Fractions I

55m 12s

Intro
0:00
Integration by Partial Fractions I
0:11
Recall the Idea of Finding a Common Denominator
0:12
Decomposing a Rational Function to Its Partial Fractions
4:10
2 Types of Rational Function: Improper & Proper
5:16
Improper Rational Function
7:26
Improper Rational Function
7:27
Proper Rational Function
11:16
Proper Rational Function & Partial Fractions
11:17
Linear Factors
14:04
Irreducible Quadratic Factors
15:02
Case 1: G(x) is a Product of Distinct Linear Factors
17:10
Example I: Integration by Partial Fractions
20:33
Case 2: D(x) is a Product of Linear Factors
40:58
Example II: Integration by Partial Fractions
44:41
Integration by Partial Fractions II

42m 57s

Intro
0:00
Case 3: D(x) Contains Irreducible Factors
0:09
Example I: Integration by Partial Fractions
5:19
Example II: Integration by Partial Fractions
16:22
Case 4: D(x) has Repeated Irreducible Quadratic Factors
27:30
Example III: Integration by Partial Fractions
30:19
VII. Differential Equations
Introduction to Differential Equations

46m 37s

Intro
0:00
Introduction to Differential Equations
0:09
Overview
0:10
Differential Equations Involving Derivatives of y(x)
2:08
Differential Equations Involving Derivatives of y(x) and Function of y(x)
3:23
Equations for an Unknown Number
6:28
What are These Differential Equations Saying?
10:30
Verifying that a Function is a Solution of the Differential Equation
13:00
Verifying that a Function is a Solution of the Differential Equation
13:01
Verify that y(x) = 4e^x + 3x² + 6x + e^π is a Solution of this Differential Equation
17:20
General Solution
22:00
Particular Solution
24:36
Initial Value Problem
27:42
Example I: Verify that a Family of Functions is a Solution of the Differential Equation
32:24
Example II: For What Values of K Does the Function Satisfy the Differential Equation
36:07
Example III: Verify the Solution and Solve the Initial Value Problem
39:47
Separation of Variables

28m 8s

Intro
0:00
Separation of Variables
0:28
Separation of Variables
0:29
Example I: Solve the Following g Initial Value Problem
8:29
Example II: Solve the Following g Initial Value Problem
13:46
Example III: Find an Equation of the Curve
18:48
Population Growth: The Standard & Logistic Equations

51m 7s

Intro
0:00
Standard Growth Model
0:30
Definition of the Standard/Natural Growth Model
0:31
Initial Conditions
8:00
The General Solution
9:16
Example I: Standard Growth Model
10:45
Logistic Growth Model
18:33
Logistic Growth Model
18:34
Solving the Initial Value Problem
25:21
What Happens When t → ∞
36:42
Example II: Solve the Following g Initial Value Problem
41:50
Relative Growth Rate
46:56
Relative Growth Rate
46:57
Relative Growth Rate Version for the Standard model
49:04
Slope Fields

24m 37s

Intro
0:00
Slope Fields
0:35
Slope Fields
0:36
Graphing the Slope Fields, Part 1
11:12
Graphing the Slope Fields, Part 2
15:37
Graphing the Slope Fields, Part 3
17:25
Steps to Solving Slope Field Problems
20:24
Example I: Draw or Generate the Slope Field of the Differential Equation y'=x cos y
22:38
VIII. AP Practic Exam
AP Practice Exam: Section 1, Part A No Calculator

45m 29s

Intro
0:00
Exam Link
0:10
Problem #1
1:26
Problem #2
2:52
Problem #3
4:42
Problem #4
7:03
Problem #5
10:01
Problem #6
13:49
Problem #7
15:16
Problem #8
19:06
Problem #9
23:10
Problem #10
28:10
Problem #11
31:30
Problem #12
33:53
Problem #13
37:45
Problem #14
41:17
AP Practice Exam: Section 1, Part A No Calculator, cont.

41m 55s

Intro
0:00
Problem #15
0:22
Problem #16
3:10
Problem #17
5:30
Problem #18
8:03
Problem #19
9:53
Problem #20
14:51
Problem #21
17:30
Problem #22
22:12
Problem #23
25:48
Problem #24
29:57
Problem #25
33:35
Problem #26
35:57
Problem #27
37:57
Problem #28
40:04
AP Practice Exam: Section I, Part B Calculator Allowed

58m 47s

Intro
0:00
Problem #1
1:22
Problem #2
4:55
Problem #3
10:49
Problem #4
13:05
Problem #5
14:54
Problem #6
17:25
Problem #7
18:39
Problem #8
20:27
Problem #9
26:48
Problem #10
28:23
Problem #11
34:03
Problem #12
36:25
Problem #13
39:52
Problem #14
43:12
Problem #15
47:18
Problem #16
50:41
Problem #17
56:38
AP Practice Exam: Section II, Part A Calculator Allowed

25m 40s

Intro
0:00
Problem #1: Part A
1:14
Problem #1: Part B
4:46
Problem #1: Part C
8:00
Problem #2: Part A
12:24
Problem #2: Part B
16:51
Problem #2: Part C
17:17
Problem #3: Part A
18:16
Problem #3: Part B
19:54
Problem #3: Part C
21:44
Problem #3: Part D
22:57
AP Practice Exam: Section II, Part B No Calculator

31m 20s

Intro
0:00
Problem #4: Part A
1:35
Problem #4: Part B
5:54
Problem #4: Part C
8:50
Problem #4: Part D
9:40
Problem #5: Part A
11:26
Problem #5: Part B
13:11
Problem #5: Part C
15:07
Problem #5: Part D
19:57
Problem #6: Part A
22:01
Problem #6: Part B
25:34
Problem #6: Part C
28:54
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Lecture Comments (2)

1 answer

Last reply by: Professor Hovasapian
Thu Dec 17, 2015 12:59 AM

Post by Gautham Padmakumar on December 12, 2015

42:00 did you forget to put the differential of x in the inequality

The Definite Integral

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
  • The Definite Integral 0:08
    • Definition to Find the Area of a Curve
    • Definition of the Definite Integral
    • Symbol for Definite Integral
    • Regions Below the x-axis
    • Associating Definite Integral to a Function
    • Integrable Function
  • Evaluating the Definite Integral 29:26
    • Evaluating the Definite Integral
  • Properties of the Definite Integral 35:24
    • Properties of the Definite Integral

Transcription: The Definite Integral

Hello, welcome back to www.educator.com, and welcome back to AP Calculus.0000

Today, we are going to talk about the definite integral, very important.0004

In the last lesson, we used the following definition to find the area under the curve.0010

Let me see, what should I do today?0015

In the last lesson, we use the following definition to find the area under a curve, f(x).0024

f(x) is the function, the curve of the function but we just say curve f(x), that is fine, on the interval ab.0055

We said that the area was equal to the limit as n goes to infinity.0065

N is the number of approximating rectangles, we take the rectangles thinner and thinner,0070

of the f(x sub 1) Δx, + f(x sub 2) to Δx, so on and so forth, f(x sub n) Δx.0076

If we have 15 rectangles, we have 15 terms in the sum.0095

Δx was the width of the particular rectangle, we just added them up.0101

I will go ahead and express this as a = the limit as n goes to infinity.0109

We have the summation notation, the shorthand for this.0114

When we picked some index i, which runs from 1 to n, whatever that happens to be.0119

F(x sub i) × Δx, here the Δx is equal to the b – a/ n.0125

It is the right endpoint of our domain, the left endpoint of our domain of our interval divided by the number of rectangles that we wanted.0137

x sub i is actually in the little sub interval x sub i - 1 x sub i.0148

All this means is that when we break up the interval, let us say we have x sub 3, and we have x sub 4,0160

something like that, and we have a over here, b over here.0170

In this interval, our x sub i is somewhere in here.0174

Sometimes, we pick the left endpoint, sometimes we pick the right endpoint.0179

Sometimes, we pick the midpoint, and that it can also be any other point in between.0183

That is all that that means, this part right here.0187

Let me go ahead and actually draw a little picture of that.0192

We have our axis, we had a curve, we had a, we had b.0198

A is the one that we called x0.0205

Let us say we had 1, 2, 3, 4, this would be our x sub 1, this would be our x sub 2, x sub 3, x sub 4,0208

and our x sub 5 is going to be our b.0221

This just means somewhere in there.0226

Our x sub 4 is going to be somewhere in that little sub interval, that is all that means.0230

We are going to define the definite integral.0241

We now define the definite integral.0251

I will go ahead and put this in red.0263

You know what, I think I want to use red.0273

I think to prefer to just go back to black, how is that?0278

We will say let f(x) be defined on the closed interval ab, divide ab into n sub intervals.0284

Everything is exactly as we did before, each of length Δx which is equal to b – a/ n.0311

We will let x sub 0 = a, then we have x1, x2, and so forth.0328

We will let x sub n = b.0338

The x sub 0 is the left endpoint, the x sub n is the right endpoint.0344

Then, the integral a to b, f(x) dx, the definite integral of the function f from a to b is equal to the limit that we had.0349

It is equal to the limit as n goes to infinity of the sum i = 1 to n of f(x sub i) Δx.0369

Again, where x sub i is in the sub interval, x sub i – 1, or the x sub i is somewhere in the interval x sub i - 1 x sub i.0384

In other words, x sub 3 is going to be somewhere between x sub 2 and x sub 3.0411

That is all that means.0420

If this limit exists, if the limit on the right exists, in other words,0422

we go through the process of finding the Δx which is the b – a/ n, we find the f(x sub i) based on the x sub i.0438

We form this thing, we form the sum of this thing, and then what we get is going to be some function of n, and then we take n to infinity.0446

If we end up getting a finite limit, if the limit exists, we say that f(x) is integrable.0454

This, the limit that we get is that definite integral of f(x).0474

If not, if the limit does not exist, then not.0485

If not, then not integrable.0489

This is the definition of the definite integral.0496

We started up with an area, we use this limit to find an area.0500

Now we are actually using this definition of area.0506

No longer is area, we are actually defining it as something that has to do with the function itself.0511

Something called the integral of that function.0519

This thing, a to b of f(x) dx is a symbol for the entire process that we go through,0527

entire process of summation + the limit as n goes to infinity.0548

This is a symbol for the entire process of forming the function, taking the sum of the function, then taking the limit.0564

Let us label a couple of things here, say what they are.0573

This thing, the f(x), this is called the integrand.0581

This right here is called the lower limit of the integral.0593

This right here, analogously, is called the upper limit of the integral.0599

When we read this, we always say the integral of f(x) from a to b, not from b to a, from bottom to top.0606

This thing, this reminds us of the independent variable.0615

If the independent variable of the function is x, this has to be dx.0628

If the independent variable of the function is r, this has to be dr.0632

Reminds us of the independent variable and is the differential version of the Δx.0636

This symbol, it is in the shape of an elongated s to remind us0675

that integration is just a long summation problem.0697

As it turns out in mathematics where the only thing that you can never ever do is add two numbers,0721

or 3 numbers, or in the case of calculus an infinite number of numbers.0725

That is what this says, this is reminding us that all we are doing,0730

when we are taking the definite integral of something is we are forming a big sum, a hundred numbers, 2000 numbers.0734

Or when we pass to the integral from the limit, when we take the limit and we passed to something else, in this case, the integral an infinite sum.0743

That is what is there to do, it is their to remind us that all we are doing is we are adding a lot of numbers together.0751

The definite integral is a number, if it exists.0761

If f(x), if the function that we happen to be dealing with is greater than 0 for all x in the particular interval ab,0784

in other words, greater than 0, it means above the x axis.0798

Then, this number just happens, that is the important thing, it just happens to be the area under a curve for f(x).0804

We started off by dealing with curves and we use this limit that we defined, the limits of the sum of such and such.0829

It turns out this integral is the deeper concept, the integral is a number.0838

It is a number that is associated with a function over a certain integral.0845

We define that number by going through this process of doing the limit.0849

It so happens that, if the function is greater than 0, the area under the curve happens to equal the integral.0853

We are not defining the integral in terms of area.0863

What we are actually doing is we introduced area first0866

to sort of give some physical conceptual motivation, for this thing that we are trying to do.0868

As opposed to just introducing that this is the integral.0875

Here, you form the sum, you take this limit and that is that.0877

That is very abstract, we start with the area.0881

We are defining this, we use that limit to define the integral.0884

It is the integral that is the deeper concept.0889

It just so happens that it happens to match the area under the curve.0894

It is the integral that is the deeper concept.0898

It can stand alone, it does not need to be associated with area.0900

As a mathematical tool that happens to give us the area, that is what is happening.0907

Let us talk about that.0915

We just said that if f(x) is bigger than 0 happens to be equal to the area.0925

But if we have something like this, let us go ahead and go this way.0930

Something like that, let us say this is a and let us say this is b.0939

Let us just call this a’ and let us call this point b’.0953

For regions from a to a’, the graph of the function is above the axis.0964

If I take the integral from here to here, I’m going to get an area.0973

The same thing here, from b’ to b, the function is above the x axis, it is positive.0977

Therefore, if I take the integral, if I take that limit, I’m going to get a and area.0983

What happens though if the function is actually below?0989

Here, the area is positive, here, the area is positive.0992

The approximating rectangles are just, you are taking some Δx and you are essentially taking some f(x).0997

F(x) is negative, what you are going to end up with is a negative area.1007

For the regions below the x axis, the area, I will go ahead and put it in quotes, is negative.1013

Because this f(x sub i) dx, because these f(x sub i), these are negative.1039

They are below the x axis.1053

F(x) here is down here, -16, -14, -307, whatever it is.1054

These are negative.1061

When you take the integral from a to b f(x) dx from here, all the way to here, which involves this and this, this is the definite integral.1070

But it does not give you the area under the curve, it is a number.1091

What it does is it gives you sort of a net area.1096

It is a net area, if you will.1102

Let us say this area here was 10 and let us say this area under here was 30.1107

Let us say this area under here was -50.1113

The integral from a to b of this function is going to be 10 - 50 + 30.1121

I mean, technically, we can go ahead and take the absolute value, if we were asked what is the area under the curve?1131

We could take 10 + the absolute value is -50 which is 50, 60, and 70, 80, 90.1138

Yes, the total area, in terms of actual physical area is 90 but the integral is not 90.1144

The integral is 10 - 50 which is -40 + 30 – 10.1152

The integral is a number, it can be associated with an area if the function as above the x axis.1158

But it does not have to be associated with an area.1164

It just so happens to be the same sort of tool that we can use to do so.1166

Integral, separate mathematical object altogether, has nothing to do with area.1170

That is the important part.1177

The definite integral is a deeper concept, I should say it is the deeper concept.1184

It is a number which we can associate with a given function on a specified interval.1208

In other words, if I gave you some f(x) and if I gave you some interval ab,1236

with that function on that interval, I can associate some number.1246

In other words, I can map a function on an interval to a number.1254

That is what this is, mathematically, that is what is happening here.1259

Given a function and the interval, I can do something to it.1264

In other words, I can integrate it.1267

What I get back, what I spit out, after I turn my crank and do whatever it is that I'm doing to this function, I get some number.1271

For functions greater than or equal to 0, we can then associate area with this number, the integral.1281

The integral comes first, the number comes first, the area afterward.1309

We just introduced it in a reverse way.1317

Note the definite integral, if integral of a function, I guess the real morale that I’m trying to push here,1328

the definite integral of a function does not have to have a physical association.1345

The definite integral exists as a mathematical object.1367

It exists as a mathematical object, independent of physical reality.1382

The mathematics that we used to describe the physical world, it is not there to describe the physical world.1396

The mathematics exists, it is a tool.1405

Whether we discovered that we can associate this math,1410

we can use it to describe the physical world but it does not come from the physical world.1414

In other words, the existence of the physical world does not give birth to mathematics.1421

Mathematics exist independently as mathematical objects.1426

It just so happens that physical reality happens to fall in line with mathematical description.1431

That is what is going.1436

The integral exists, it happens to be associated with an area, if we needed to.1439

As we will see later on in future lessons, it is going to be associated with more than just area.1443

It is going to be associated with volumes and all kinds of things, which is why calculus is so incredibly powerful.1448

Let us say a little bit more.1461

We chose Δx = b – a/ n, in other words, I should that is, we made Δx the same width for every integral.1464

Δx the same for every approximating rectangle.1489

They do not have to be equal, they do not have to be the same.1510

Always approximating rectangles, we made them that way, of uniform width,1522

simply to make our lives easier so that we can actually do some work, do some math.1526

They do not have to be the same, each one can be different.1533

You actually end up getting the same answer.1535

They do not have to be the same, it simply makes things easier to handle.1539

Yes, that is the only reason.1543

It simply makes things easier to handle.1546

Also, we said that x sub i is in x sub i -1 to x sub i.1560

By choosing right endpoints, in other words by choosing x sub i as the right endpoint of that particular sub interval, that is x sub i = x sub i,1580

again, we just make things easier and we make things more uniform, more consistent.1611

It is not so haphazard, not without just taking random points.1622

We are being nice and systematic.1625

In any sub interval, we take the right endpoint.1626

That is it, nice and systematic, keep things orderly.1629

Again, we just make things easier.1630

Or I should say, not every function is integrable.1640

Just because a function exists, it does not mean that we can actually integrate it.1644

In other words, when we run through the process of finding it, taking the summation, taking the limit, the limit may not exist.1650

Not every function is integrable.1656

Our theorem, if f(x) is continuous on the closed interval ab, if it is continuous,1667

or if f(x) contains at most a finite number of discontinuities,1698

the operative word being finite, then f(x) is integrable.1723

We have a criteria now to decide whether a function is integrable or not.1734

If the function is continuous on its domain, on its domain of definition, on its interval that we have chosen.1739

If it is continuous, it is integrable, I can integrate it.1744

I can find the number associated with it.1749

Or if that function on its sub interval, the ab has a finite number of discontinuities, I can integrate it, it is integrable.1750

For now, we will evaluate the integrals, the definite integrals.1768

We will evaluate the definite integral using the definition.1787

In other words, we will use the summation limit.1798

We will use the definition to evaluate these things.1799

It is going to be a little tedious, but that is fine.1802

We want to get some sense of what is actually involved here, using the definition.1805

Later of course, the same way that we did with differentiation.1813

Remember, we have the differentiation, we formed the quotient f(x) + h – f(x) divided by h.1816

We simplified that, then we took the limit, that gave us the derivative.1822

That is the definition of the derivative.1825

Then, we came up with my simple quick ways of finding the derivative.1827

We will do the same here.1830

We are going to use the definition first and get our feet wet with that, just to get a sense of what is going on.1831

And then, we are going to come up with quick ways of doing the integration.1836

You have actually already done some of them, antiderivatives.1840

An antiderivative is the integral, that is what is going to be happening.1843

For now, we will evaluate the definite integral using the definition.1848

As such, we may need the following to help us.1853

We may need the following properties to help us.1861

If I have a sum i goes from 1 to n of i, there is a closed form expression for that.1878

It is going to be n × n + 1/ 2.1886

In other words, what this is saying is that, if I take, let us say n is 15.1890

If I say, out of the numbers from 1 to 15, 1 + 2 + 3 + 4 + 5 + 6 . . . + 13 + 14 + 15,1894

if I add all of those up, I can actually just take 15 × 16 and divide by 2.1902

This gives me a closed form expression for the sum, that is all this is.1908

Just some formulas that are going to help us along.1914

I have another one, the sum as i goes from 1 to n of i², that also gives us a closed form expression.1921

+ 1 to 1 + 1/ 6.1930

I happen to have a closed form expression for i = 1 to n of i³.1936

If I take 1³ + 2³ + 3³ + 4³ + 5³, however high I want to go, that is going to be n × n + 1/ 2².1942

Let us see b as a constant, if c is a constant and if I have the summation as i goes from 1 to n,1963

I have just plain old c, no i anywhere, that is just equal to n × c.1977

It is just telling me, i = 1, let us say n is 10, that means add c 10 times.1985

C + c + c + c and another 5×, that is 10 × c, n × c.1991

This is just a formula for, when I see this, I can substitute this.1999

That is all we are doing here.2005

It is just writing down some formulas that we can use, when we actually start evaluating these integrals using the definition.2007

Another thing that we can do is 1 to n c × ai, if I have some expression that involves a c, I can pull the constant out in front of it.2015

The same that I do, when I distribute.2029

When I factor things out, I can factor out this c.2032

Because this is just ca sub 1, ca sub 2 + ca sub 3.2035

They all involve c, just pull the c out.2041

It equal c × the sum i = 1 to n of a sub i.2045

What this means is that you can pull a constant out from under the summation symbol.2052

Let us do the sum as i go from 1 to n.2089

If we have a sub i + b sub i, let us say + or -, I can separate these out.2095

I can write this as, the sum i go from 1 to n of a sub i, + or -, depending on whether it is + or -.2102

In other words, the summation distributes over both.2108

You can think of it that way, b sub i 1 to n.2113

Properties of the definite integral.2120

Let us go to properties of the definite integral.2123

These are all going to be very familiar because integration is just a fancy form of summation.2136

The summation symbols, everything that we do for summation, we can do for the integral.2142

The integral from b to a of f(x) dx is equal to the negative of the integral from a to b of f(x) dx.2154

In other words, if I switch the order of integration, if I do here, my Δx is b – a/ n.2166

Here it is b – a/ n, here it is going to be a – b/ n.2177

If I integrate from b to a, instead of from a to b, all I do is switch the sign of the integral.2184

That is it, very simple, that is all.2188

In calculus, we are adding from left to right.2193

We have some function and we have broken up into a bunch of rectangles.2199

If I add in this direction from a to b, I get a number.2202

If I decide to add in this direction, I get the negative of that number.2206

That is all this is saying, switch the upper and lower limit, change the sign.2210

The integral from a to a of f(x) dx that is equal to 0.2219

The integral from a to b of cdx, c is any constant, that is just equal to c × b – a.2227

All this says is, if I have a constant function from a to b, the integral, it is just c,2239

the value of c which is this height × this distance, the area.2251

Or it could be negative because it is the integral, integral.2257

Now we are thinking, areas can now be negative.2260

If we introduce this notion of a negative area, it is not a problem.2263

Some further properties, the integral from a to b of c × f(x) dx, you can pull the constant out, c × the integral from a to b of f(x) dx.2269

The integral from a to b of f(x) + g(x) dx, the integral of a sum is equal to the sum of the individual integrals.2288

In other words, the integral sign distributes over both.2301

I will just write up the whole thing, of f(x) dx + the integral from a to b of g(x) dx.2311

The integral from a to c of f(x) dx = the integral from a to b of f(x) dx + the integral from b to c of f(x) dx.2326

This last one says I can actually break this up.2341

If I have a here and if I have c here, if i have b here, and if that is my function,2345

the integral from a to c is just the integral from a to b + the integral from b to c.2353

That is all I’m doing, just adding them up.2358

If f(x) is greater than or equal to 0 on the interval ab, then the integral of f(x) dx is greater than or equal to 0.2370

Very simple, nothing happening here.2391

Integration is something called an operator.2396

An operator is just a fancy word for do something to this function, in other words, operate on it.2403

If I give you a function f(x) and I say integrate it, integrate it means do something to it.2408

Take this function through a series of steps and spit out a number at the end.2412

When you see f(x) is greater than or equal to 0, you already know from years and years, elementary, junior high school math,2418

that whenever you have an quality or an inequality, as long as you do the same thing to both sides of the quality or the inequality,2426

you retain that equality or inequality.2436

Here, f(x) is greater than or equal to 0.2439

If I integrate the left side, integrate the right side, I get the left side of the integral of f(x) dx.2441

The integral that of 0 is just a bunch of 0 added together.2449

It is 0, it stays.2453

Think about it that way.2456

When you see an equality or inequality, you can integrate both sides.2458

It retains the equality or inequality, it retains the relationship.2463

Just like if you take the logarithm of both sides, if you exponentiate both sides, if you multiply both sides by 2,2467

if you divide both sides by 5, as long as you do it to both sides, you are fine.2472

Treat the integral as some operator, as some thing that you do.2477

If f(x) is greater than or equal to g(x) on ab, then exactly what you think.2484

The interval from a to b of f(x) is greater than or equal to the integral from a to b of g(x).2499

This is greater than that so the integral is greater than integral, very simple.2508

If m is less than or equal to f(x), less than or equal to M on ab,2516

then m × b - a less than or equal to the integral a to b, f(x) dx less than or equal to m × b – a.2532

If some function on this interval happens to have a lower bound and an upper bound,2548

then the integral of that function is going to be greater than the lower bound × the length of the interval.2555

It is going to be less than the upper bound × the length of the interval.2563

All we have done here is take the integral of this, the integral of that, the integral of that.2567

The integral of that, that is the symbol.2571

The integral of a constant m dx, we said it is equal to m × b – a.2574

The integral of M is M × b – a.2579

Just integrate, integrate, solve for the things you can solve and leave those that you cannot, as the symbol.2587

Thank you so much for joining us here at www.educator.com.2596

We will see you next time, bye.2599

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