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### How to Antidifferentiate Any Polynomial Using the Sum, Constant Multiple, and Power Rules

The anti-differentiation rules for integrating greatly limit how many integrals you can compute easily. In many cases, however, you can integrate *any* polynomial in three steps by using the Sum Rule, Constant [more…]

### How to Use Identities to Integrate Trigonometry Functions

You’ll be surprised how much headway you can often make when you integrate an unfamiliar trigonometry function by first tweaking it using the Basic Five trig identities: [more…]

### Computing Integrals and Representing Integrals as Functions

In trying to understand what makes a function integrable, you first need to understand two related issues: difficulties in *computing integrals* and *representing integrals as functions.* [more…]

### Understanding What Makes a Function Integrable

When mathematicians discuss whether a function is integrable, they aren’t talking about the difficulty of computing that integral — or even whether a method has been discovered. Each year, mathematicians [more…]

### Use a Shortcut for Integrating Compositions of Functions

You can use a shortcut to integrate compositions of functions — that is, nested functions of the form *f*(*g*(*x*)). Technically, you’re using the variable substitution [more…]

### Using the Product Rule to Integrate the Product of Two Functions

The Product Rule enables you to integrate the product of two functions. For example, through a series of mathematical somersaults, you can turn the following equation into a formula that’s useful for integrating [more…]

### How to Integrate Even Powers of Secants with Tangents

You can integrate even powers of secants with tangents. If you wanted to integrate tan^{m}*x*sec^{n}*x* when *n* is even — for example, tan^{8} *x* sec^{6} *x* — you would follow these steps: [more…]

### How to Integrate Odd Powers of Tangents with Secants

You can integrate odd powers of tangents with secants. To integrate tan^{m}*x* sec^{n}*x* when *m* is odd — for example, tan^{7}*x* sec^{9} *x* — you would follow these steps: [more…]

### Using Trigonometry Substitution to Integrate a Function

Trig substitution allows you to integrate a whole slew of functions that you can’t integrate otherwise. These functions have a special, uniquely scary look about them and are variations on these three [more…]

### Integrate a Function Using the Secant Case

When the function that you’re integrating includes a term of the form (*bx*^{2} – *a*^{2})^{n}, draw your trig substitution triangle for the *secant case.* For example, suppose that you want to evaluate this integral [more…]

### Knowing When to Avoid Trigonometry Substitution

It’s useful to know when you should avoid using trig substitution. With some integrals, it’s better to expand the problem into a polynomial. For example, look at the following integral: [more…]

### Setting Up Partial Fractions When You Have Distinct Linear Factors

Your first step in any problem that involves partial fractions is to recognize which case you’re dealing with so that you can solve the problem. The simplest case in which partial fractions are helpful [more…]

### How to Distinguish Proper and Improper Rational Expressions

Integration by partial fractions works only with *proper rational expressions,* but not with *improper rational expressions**.* Telling a proper fraction from an improper one is easy: A fraction a/b is proper [more…]

### Finding the Integral of a Product of Two Functions

Sometimes the function that you’re trying to integrate is the product of two functions — for example, sin^{3}*x* and cos *x.* This would be simple to differentiate with the Product Rule, but integration doesn’t [more…]

### How to Integrate a Function Multiplied by a Set of Nested Functions

Sometimes you need to integrate the product of a function (*x*) and a composition of functions (for example, the function 3*x*^{2} + 7 nested inside a square root function). If you were differentiating, you could [more…]

### How to Integrate Compositions of Functions

*Compositions of functions* — that is, one function nested inside another — are of the form *f*(*g*(*x*)). You can integrate them by substituting *u* = *g*(*x*) when [more…]

### Substituting with Expressions of the Form *f*(*x*) Multiplied by *g*(*x*)

When *g*'(*x*) = *f*(*x*), you can use the substitution *u* = *g*(*x*) to integrate expressions of the form *f*(*x*) multiplied by *g*(*x*). Variable substitution helps to fill the gaps left by the absence of a Product Rule [more…]

### Substituting with Expressions of the Form *f*(*x*) Multiplied by *h*(*g*(*x*))

When *g*'(*x*) = *f*(*x*), you can use the substitution *u* = *g*(*x*) to integrate expressions of the form *f*(*x*) multiplied by *h*(*g*(*x*)), provided that *h* is a function that you already know how to integrate. [more…]

### Using Variable Substitution to Evaluate Definite Integrals

When using variable substitution to evaluate a definite integral, you can save yourself some trouble at the end of the problem. Specifically, you can leave the solution in terms of [more…]

### Knowing When to Integrate by Parts

It’s important to recognize when integrating by parts is useful. To start off, here are two important cases when integration by parts is definitely the way to go: [more…]

### How to Integrate Odd Powers of Sines and Cosines

You can integrate *any* function of the form sin^{m}*x* cos^{n}*x*when *m* is odd, for any real value of *n.* For this procedure, keep in mind the handy trig identity sin [more…]

### How to Integrate Even Powers of Sines and Cosines

You can integrate even powers of sines and cosines. For example, if you wanted to integrate sin^{2} *x* and cos^{2} *x,* you would use these two half-angle trigonometry identities: [more…]

### Using Identities to Express a Trigonometry Function as a Pair of Functions

You can express every product of powers of trig functions, no matter how weird, as the product of any pair of trig functions. The three most useful pairings are sine and cosine, tangent and secant, and [more…]

### How to Integrate Rational Expressions Using the Sum, Constant Multiple, and Power Rules

In many cases, you can untangle hairy rational expressions and integrate them using the anti-differentiation rules plus the Sum Rule, Constant Multiple Rule, and Power Rule. [more…]

### When to Use Variable Substitution with Integrals

Variable substitution comes in handy for some integrals. The anti-differentiation formulas plus the Sum Rule, Constant Multiple Rule, and Power Rule allow you to integrate a variety of common functions [more…]