Calculus Examples

$\int \frac{x^{4}}{1 + x} d x$

Step 1

Reorder $1$ and $x$ .

$\int \frac{x^{4}}{x + 1} d x$

Step 2

Divide $x^{4}$ by $x + 1$ .

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Step 2.1

Set up the polynomials to be divided. If there is not a term for every exponent, insert one with a value of $0$ .

$x$

$1$

$x^{4}$

$0 x^{3}$

$0 x^{2}$

$0 x$

$0$

Step 2.2

Divide the highest order term in the dividend $x^{4}$ by the highest order term in divisor $x$ .

$x^{3}$

$x$

$1$

$x^{4}$

$0 x^{3}$

$0 x^{2}$

$0 x$

$0$

Step 2.3

Multiply the new quotient term by the divisor.

$x^{3}$

$x$

$1$

$x^{4}$

$0 x^{3}$

$0 x^{2}$

$0 x$

$0$

$x^{4}$

$x^{3}$

Step 2.4

The expression needs to be subtracted from the dividend, so change all the signs in $x^{4} + x^{3}$

$x^{3}$

$x$

$1$

$x^{4}$

$0 x^{3}$

$0 x^{2}$

$0 x$

$0$

$x^{4}$

$x^{3}$

Step 2.5

After changing the signs, add the last dividend from the multiplied polynomial to find the new dividend.

$x^{3}$

$x$

$1$

$x^{4}$

$0 x^{3}$

$0 x^{2}$

$0 x$

$0$

$x^{4}$

$x^{3}$

Step 2.6

Pull the next terms from the original dividend down into the current dividend.

$x^{3}$

$x$

$1$

$x^{4}$

$0 x^{3}$

$0 x^{2}$

$0 x$

$0$

$x^{4}$

$x^{3}$

$0 x^{2}$

Step 2.7

Divide the highest order term in the dividend $- x^{3}$ by the highest order term in divisor $x$ .

$x^{3}$

$x^{2}$

$x$

$1$

$x^{4}$

$0 x^{3}$

$0 x^{2}$

$0 x$

$0$

$x^{4}$

$x^{3}$

$0 x^{2}$

Step 2.8

Multiply the new quotient term by the divisor.

$x^{3}$

$x^{2}$

$x$

$1$

$x^{4}$

$0 x^{3}$

$0 x^{2}$

$0 x$

$0$

$x^{4}$

$x^{3}$

$0 x^{2}$

$x^{3}$

$x^{2}$

Step 2.9

The expression needs to be subtracted from the dividend, so change all the signs in $- x^{3} - x^{2}$

$x^{3}$

$x^{2}$

$x$

$1$

$x^{4}$

$0 x^{3}$

$0 x^{2}$

$0 x$

$0$

$x^{4}$

$x^{3}$

$0 x^{2}$

$x^{3}$

$x^{2}$

Step 2.10

After changing the signs, add the last dividend from the multiplied polynomial to find the new dividend.

$x^{3}$

$x^{2}$

$x$

$1$

$x^{4}$

$0 x^{3}$

$0 x^{2}$

$0 x$

$0$

$x^{4}$

$x^{3}$

$0 x^{2}$

$x^{3}$

$x^{2}$

Step 2.11

Pull the next terms from the original dividend down into the current dividend.

$x^{3}$

$x^{2}$

$x$

$1$

$x^{4}$

$0 x^{3}$

$0 x^{2}$

$0 x$

$0$

$x^{4}$

$x^{3}$

$0 x^{2}$

$x^{3}$

$x^{2}$

$0 x$

Step 2.12

Divide the highest order term in the dividend $x^{2}$ by the highest order term in divisor $x$ .

$x^{3}$

$x^{2}$

$x$

$1$

$x^{4}$

$0 x^{3}$

$0 x^{2}$

$0 x$

$0$

$x^{4}$

$x^{3}$

$0 x^{2}$

$x^{3}$

$x^{2}$

$0 x$

Step 2.13

Multiply the new quotient term by the divisor.

$x^{3}$

$x^{2}$

$x$

$1$

$x^{4}$

$0 x^{3}$

$0 x^{2}$

$0 x$

$0$

$x^{4}$

$x^{3}$

$0 x^{2}$

$x^{3}$

$x^{2}$

$0 x$

$x^{2}$

$x$

Step 2.14

The expression needs to be subtracted from the dividend, so change all the signs in $x^{2} + x$

$x^{3}$

$x^{2}$

$x$

$1$

$x^{4}$

$0 x^{3}$

$0 x^{2}$

$0 x$

$0$

$x^{4}$

$x^{3}$

$0 x^{2}$

$x^{3}$

$x^{2}$

$0 x$

$x^{2}$

$x$

Step 2.15

After changing the signs, add the last dividend from the multiplied polynomial to find the new dividend.

$x^{3}$

$x^{2}$

$x$

$1$

$x^{4}$

$0 x^{3}$

$0 x^{2}$

$0 x$

$0$

$x^{4}$

$x^{3}$

$0 x^{2}$

$x^{3}$

$x^{2}$

$0 x$

$x^{2}$

$x$

Step 2.16

Pull the next terms from the original dividend down into the current dividend.

$x^{3}$

$x^{2}$

$x$

$1$

$x^{4}$

$0 x^{3}$

$0 x^{2}$

$0 x$

$0$

$x^{4}$

$x^{3}$

$0 x^{2}$

$x^{3}$

$x^{2}$

$0 x$

$x^{2}$

$x$

$0$

Step 2.17

Divide the highest order term in the dividend $- x$ by the highest order term in divisor $x$ .

$x^{3}$

$x^{2}$

$x$

$1$

$x$

$1$

$x^{4}$

$0 x^{3}$

$0 x^{2}$

$0 x$

$0$

$x^{4}$

$x^{3}$

$0 x^{2}$

$x^{3}$

$x^{2}$

$0 x$

$x^{2}$

$x$

$0$

Step 2.18

Multiply the new quotient term by the divisor.

$x^{3}$

$x^{2}$

$x$

$1$

$x$

$1$

$x^{4}$

$0 x^{3}$

$0 x^{2}$

$0 x$

$0$

$x^{4}$

$x^{3}$

$0 x^{2}$

$x^{3}$

$x^{2}$

$0 x$

$x^{2}$

$x$

$0$

$x$

$1$

Step 2.19

The expression needs to be subtracted from the dividend, so change all the signs in $- x - 1$

$x^{3}$

$x^{2}$

$x$

$1$

$x$

$1$

$x^{4}$

$0 x^{3}$

$0 x^{2}$

$0 x$

$0$

$x^{4}$

$x^{3}$

$0 x^{2}$

$x^{3}$

$x^{2}$

$0 x$

$x^{2}$

$x$

$0$

$x$

$1$

Step 2.20

After changing the signs, add the last dividend from the multiplied polynomial to find the new dividend.

$x^{3}$

$x^{2}$

$x$

$1$

$x$

$1$

$x^{4}$

$0 x^{3}$

$0 x^{2}$

$0 x$

$0$

$x^{4}$

$x^{3}$

$0 x^{2}$

$x^{3}$

$x^{2}$

$0 x$

$x^{2}$

$x$

$0$

$x$

$1$

Step 2.21

The final answer is the quotient plus the remainder over the divisor.

$\int x^{3} - x^{2} + x - 1 + \frac{1}{x + 1} d x$

Step 3

Split the single integral into multiple integrals.

$\int x^{3} d x + \int - x^{2} d x + \int x d x + \int - 1 d x + \int \frac{1}{x + 1} d x$

Step 4

By the Power Rule, the integral of $x^{3}$ with respect to $x$ is $\frac{1}{4} x^{4}$ .

$\frac{1}{4} x^{4} + C + \int - x^{2} d x + \int x d x + \int - 1 d x + \int \frac{1}{x + 1} d x$

Step 5

Since $- 1$ is constant with respect to $x$ , move $- 1$ out of the integral.

$\frac{1}{4} x^{4} + C - \int x^{2} d x + \int x d x + \int - 1 d x + \int \frac{1}{x + 1} d x$

Step 6

By the Power Rule, the integral of $x^{2}$ with respect to $x$ is $\frac{1}{3} x^{3}$ .

$\frac{1}{4} x^{4} + C - (\frac{1}{3} x^{3} + C) + \int x d x + \int - 1 d x + \int \frac{1}{x + 1} d x$

Step 7

By the Power Rule, the integral of $x$ with respect to $x$ is $\frac{1}{2} x^{2}$ .

$\frac{1}{4} x^{4} + C - (\frac{1}{3} x^{3} + C) + \frac{1}{2} x^{2} + C + \int - 1 d x + \int \frac{1}{x + 1} d x$

Step 8

Combine $\frac{1}{3}$ and $x^{3}$ .

$\frac{1}{4} x^{4} + C - (\frac{x^{3}}{3} + C) + \frac{1}{2} x^{2} + C + \int - 1 d x + \int \frac{1}{x + 1} d x$

Step 9

Apply the constant rule.

$\frac{1}{4} x^{4} + C - (\frac{x^{3}}{3} + C) + \frac{1}{2} x^{2} + C - x + C + \int \frac{1}{x + 1} d x$

Step 10

Let $u = x + 1$ . Then $d u = d x$ . Rewrite using $u$ and $d$ $u$ .

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Step 10.1

Let $u = x + 1$ . Find $\frac{d u}{d x}$ .

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Step 10.1.1

Differentiate $x + 1$ .

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

Step 10.1.2

By the Sum Rule, the derivative of $x + 1$ with respect to $x$ is $\frac{d}{d x} [x] + \frac{d}{d x} [1]$ .

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

Step 10.1.3

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

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

Step 10.1.4

Since $1$ is constant with respect to $x$ , the derivative of $1$ with respect to $x$ is $0$ .

$1 + 0$

Step 10.1.5

Add $1$ and $0$ .

$1$

Step 10.2

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

$\frac{1}{4} x^{4} + C - (\frac{x^{3}}{3} + C) + \frac{1}{2} x^{2} + C - x + C + \int \frac{1}{u} d u$

Step 11

The integral of $\frac{1}{u}$ with respect to $u$ is $\ln (| u |)$ .

$\frac{1}{4} x^{4} + C - (\frac{x^{3}}{3} + C) + \frac{1}{2} x^{2} + C - x + C + \ln (| u |) + C$

Step 12

Simplify.

$\frac{1}{4} x^{4} - \frac{1}{3} x^{3} + \frac{1}{2} x^{2} - x + \ln (| u |) + C$

Step 13

Replace all occurrences of $u$ with $x + 1$ .

$\frac{1}{4} x^{4} - \frac{1}{3} x^{3} + \frac{1}{2} x^{2} - x + \ln (| x + 1 |) + C$