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The Fundamental Theorem of Calculus
Three Different Concepts
The Fundamental Theorem of Calculus (Part 2)
The Fundamental Theorem of Calculus (Part 1)
More FTC 1
The Indefinite Integral and the Net Change
Indefinite Integrals and Anti-derivatives
A Table of Common Anti-derivatives
The Net Change Theorem
The NCT and Public Policy
Substitution
Substitution for Indefinite Integrals
Examples to Try
Revised Table of Integrals
Substitution for Definite Integrals
Examples
Area Between Curves
Computation Using Integration
To Compute a Bulk Quantity
The Area Between Two Curves
Horizontal Slicing
Summary
Volumes
Slicing and Dicing Solids
Solids of Revolution 1: Disks
Solids of Revolution 2: Washers
More Practice
Integration by Parts
Integration by Parts
Examples
Integration by Parts with a definite integral
Going in Circles
Tricks of the Trade
Integrals of Trig Functions
Antiderivatives of Basic Trigonometric Functions
Product of Sines and Cosines (mixed even and odd powers or only
odd powers)
Product of Sines and Cosines (only even powers)
Product of Secants and Tangents
Other Cases
Trig Substitutions
How Trig Substitution Works
Summary of trig substitution options
Examples
Completing the Square
Partial Fractions
Introduction
Linear Factors
Irreducible Quadratic Factors
Improper Rational Functions and Long Division
Summary
Strategies of Integration
Substitution
Integration by Parts
Trig Integrals
Trig Substitutions
Partial Fractions
Improper Integrals
Type 1 - Improper Integrals with Infinite Intervals of
Integration
Type 2 - Improper Integrals with Discontinuous Integrands
Comparison Tests for Convergence
Differential Equations
Introduction
Separable Equations
Mixing and Dilution
Models of Growth
Exponential Growth and Decay
Logistic Growth
Infinite Sequences
Approximate Versus Exact Answers
Examples of Infinite Sequences
Limit Laws for Sequences
Theorems for and Examples of Computing Limits of Sequences
Monotonic Covergence
Infinite Series
Introduction
Geometric Series
Limit Laws for Series
Test for Divergence and Other Theorems
Telescoping Sums and the FTC
Integral Test
Road Map
The Integral Test
Estimates of Value of the Series
Comparison Tests
The Basic Comparison Test
The Limit Comparison Test
Convergence of Series with Negative Terms
Introduction, Alternating Series,and the AS Test
Absolute Convergence
Rearrangements
The Ratio and Root Tests
The Ratio Test
The Root Test
Examples
Strategies for testing Series
Strategy to Test Series and a Review of Tests
Examples, Part 1
Examples, Part 2
Power Series
Radius and Interval of Convergence
Finding the Interval of Convergence
Power Series Centered at x=a
Representing Functions as Power Series
Functions as Power Series
Derivatives and Integrals of Power Series
Applications and Examples
Taylor and Maclaurin Series
The Formula for Taylor Series
Taylor Series for Common Functions
Adding, Multiplying, and Dividing Power Series
Miscellaneous Useful Facts
Applications of Taylor Polynomials
Taylor Polynomials
When Functions Are Equal to Their Taylor Series
When a Function Does Not Equal Its Taylor Series
Other Uses of Taylor Polynomials
Partial Derivatives
Visualizing Functions in 3 Dimensions
Definitions and Examples
An Example from DNA
Geometry of Partial Derivatives
Higher Order Derivatives
Differentials and Taylor Expansions
Multiple Integrals
Background
What is a Double Integral?
Volumes as Double Integrals
Iterated Integrals over Rectangles
How To Compute Iterated Integrals
Examples of Iterated Integrals
Cavalieri's Principle
Fubini's Theorem
Summary and an Important Example
Double Integrals over General Regions
Type I and Type II regions
Examples 1-4
Examples 5-7
Order of Integration
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Cavalieri's Principle
This section explains a second way to see the relation between
double integrals and interated integrals.
(You may or may not need to learn
Cavalieri's Principle -- check with your instructor.)
An alternate approach to finding volumes (and hence double
integrals) - the so-called Slice Method
- was formulated by Cavalieri and is expressed mathematically in
Cavalieri's Principle: let W
be a solid and Px,a≤x≤b, be a family of
parallel planes such that
- W lies between Pa and Pb,
- the area of the cross-sectional slice of W cut by
Px is A(x).
Then volume of W = ∫baA(x)dx. |
We already used this idea to compute volumes
of revolution. Suppose W is created by
rotating the graph of y=f(x),a≤x≤b, about the
x-axis. When Px is a plane perpendicular to the x-axis,
then the slice of W cut by Px is a disk of radius f(x).
Here A(x)=πf(x)2, so we recover the familiar result volume of W = π∫baf(x)2dx for a volume of
revolution. But Cavalieri's Principle does not require the
cross-sections to be triangles or disks, as we will see.
We consider an example that we already
computed as an iterated integral.
Example: Find the volume
of the solid W under the hyperbolic paraboloid z = f(x,y) = 2+x2−y2 and over the square D=[−1,1]×[−1,1]. |
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Solution: When Px is the
vertical slice perpendicular to the x-axis for fixed x
shown in purple, then A(x)=∫1−1(2+x2−y2)dy =[2y+x2y−y33]1−1=103+2x2. But
then by using the slider to fill out the solid, Cavalieri's
Principle shows that W has volume = ∫1−1A(x)dx = ∫1−1(103+2x2)dx = [10x3+2x33]1−1 = 8. |
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In other words, the volume of a region is ∫baA(x)dx,
where A(x) is the cross-sectional area at a particular value of
x. But that's the area under the curve z=f(x,y), where we are
treating x as a constant and y as our variable. That is,
The double
integral ∬ equals
the iterated integral \displaystyle\int_a^b \left
(\int_c^d f(x,y) \,dy\right )\, dx. |
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