Calculus Examples

$\frac{9}{{(x + 2)}^{2}} d x$

Step 1

Since $9$ is constant with respect to $x$ , move $9$ out of the integral.

$9 \int \frac{1}{{(x + 2)}^{2}} d x$

Step 2

Let $u = x + 2$ . Then $d u = d x$ . Rewrite using $u$ and $d$ $u$ .

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Step 2.1

Let $u = x + 2$ . Find $\frac{d u}{d x}$ .

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Step 2.1.1

Differentiate $x + 2$ .

$\frac{d}{d x} [x + 2]$

Step 2.1.2

By the Sum Rule, the derivative of $x + 2$ with respect to $x$ is $\frac{d}{d x} [x] + \frac{d}{d x} [2]$ .

$\frac{d}{d x} [x] + \frac{d}{d x} [2]$

Step 2.1.3

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 1$ .

$1 + \frac{d}{d x} [2]$

Step 2.1.4

Since $2$ is constant with respect to $x$ , the derivative of $2$ with respect to $x$ is $0$ .

$1 + 0$

Step 2.1.5

Add $1$ and $0$ .

$1$

Step 2.2

Rewrite the problem using $u$ and $d u$ .

$9 \int \frac{1}{u^{2}} d u$

Step 3

Apply basic rules of exponents.

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Step 3.1

Move $u^{2}$ out of the denominator by raising it to the $- 1$ power.

$9 \int {(u^{2})}^{- 1} d u$

Step 3.2

Multiply the exponents in ${(u^{2})}^{- 1}$ .

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Step 3.2.1

Apply the power rule and multiply exponents, ${(a^{m})}^{n} = a^{m n}$ .

$9 \int u^{2 \cdot - 1} d u$

Step 3.2.2

Multiply $2$ by $- 1$ .

$9 \int u^{- 2} d u$

Step 4

By the Power Rule, the integral of $u^{- 2}$ with respect to $u$ is $- u^{- 1}$ .

$9 (- u^{- 1} + C)$

Step 5

Simplify.

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Step 5.1

Rewrite $9 (- u^{- 1} + C)$ as $9 (- \frac{1}{u}) + C$ .

$9 (- \frac{1}{u}) + C$

Step 5.2

Simplify.

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Step 5.2.1

Multiply $- 1$ by $9$ .

$- 9 \frac{1}{u} + C$

Step 5.2.2

Combine $- 9$ and $\frac{1}{u}$ .

$\frac{- 9}{u} + C$

Step 5.2.3

Move the negative in front of the fraction.

$- \frac{9}{u} + C$

Step 6

Replace all occurrences of $u$ with $x + 2$ .

$- \frac{9}{x + 2} + C$