Calculus Examples

$\int \frac{4 x^{3}}{2 x + 3} d x$

Step 1

Since $4$ is constant with respect to $x$ , move $4$ out of the integral.

$4 \int \frac{x^{3}}{2 x + 3} d x$

Step 2

Divide $x^{3}$ by $2 x + 3$ .

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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 $0$ .

$2 x$

$3$

$x^{3}$

$0 x^{2}$

$0 x$

$0$

Step 2.2

Divide the highest order term in the dividend $x^{3}$ by the highest order term in divisor $2 x$ .

					$\frac{x^{2}}{2}$
	$2 x$	+	$3$		$x^{3}$	+	$0 x^{2}$	+	$0 x$	+	$0$

Step 2.3

Multiply the new quotient term by the divisor.

				$\frac{x^{2}}{2}$
$2 x$	+	$3$		$x^{3}$	+	$0 x^{2}$	+	$0 x$	+	$0$
			+	$x^{3}$	+	$\frac{3 x^{2}}{2}$

Step 2.4

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

				$\frac{x^{2}}{2}$
$2 x$	+	$3$		$x^{3}$	+	$0 x^{2}$	+	$0 x$	+	$0$
			-	$x^{3}$	-	$\frac{3 x^{2}}{2}$

Step 2.5

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

				$\frac{x^{2}}{2}$
$2 x$	+	$3$		$x^{3}$	+	$0 x^{2}$	+	$0 x$	+	$0$
			-	$x^{3}$	-	$\frac{3 x^{2}}{2}$
					-	$\frac{3 x^{2}}{2}$

Step 2.6

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

				$\frac{x^{2}}{2}$
$2 x$	+	$3$		$x^{3}$	+	$0 x^{2}$	+	$0 x$	+	$0$
			-	$x^{3}$	-	$\frac{3 x^{2}}{2}$
					-	$\frac{3 x^{2}}{2}$	+	$0 x$

Step 2.7

Divide the highest order term in the dividend $- \frac{3 x^{2}}{2}$ by the highest order term in divisor $2 x$ .

				$\frac{x^{2}}{2}$	-	$\frac{3 x}{4}$
$2 x$	+	$3$		$x^{3}$	+	$0 x^{2}$	+	$0 x$	+	$0$
			-	$x^{3}$	-	$\frac{3 x^{2}}{2}$
					-	$\frac{3 x^{2}}{2}$	+	$0 x$

Step 2.8

Multiply the new quotient term by the divisor.

				$\frac{x^{2}}{2}$	-	$\frac{3 x}{4}$
$2 x$	+	$3$		$x^{3}$	+	$0 x^{2}$	+	$0 x$	+	$0$
			-	$x^{3}$	-	$\frac{3 x^{2}}{2}$
					-	$\frac{3 x^{2}}{2}$	+	$0 x$
					-	$\frac{3 x^{2}}{2}$	-	$\frac{9 x}{4}$

Step 2.9

The expression needs to be subtracted from the dividend, so change all the signs in $- \frac{3 x^{2}}{2} - \frac{9 x}{4}$

				$\frac{x^{2}}{2}$	-	$\frac{3 x}{4}$
$2 x$	+	$3$		$x^{3}$	+	$0 x^{2}$	+	$0 x$	+	$0$
			-	$x^{3}$	-	$\frac{3 x^{2}}{2}$
					-	$\frac{3 x^{2}}{2}$	+	$0 x$
					+	$\frac{3 x^{2}}{2}$	+	$\frac{9 x}{4}$

Step 2.10

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

				$\frac{x^{2}}{2}$	-	$\frac{3 x}{4}$
$2 x$	+	$3$		$x^{3}$	+	$0 x^{2}$	+	$0 x$	+	$0$
			-	$x^{3}$	-	$\frac{3 x^{2}}{2}$
					-	$\frac{3 x^{2}}{2}$	+	$0 x$
					+	$\frac{3 x^{2}}{2}$	+	$\frac{9 x}{4}$
							+	$\frac{9 x}{4}$

Step 2.11

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

				$\frac{x^{2}}{2}$	-	$\frac{3 x}{4}$
$2 x$	+	$3$		$x^{3}$	+	$0 x^{2}$	+	$0 x$	+	$0$
			-	$x^{3}$	-	$\frac{3 x^{2}}{2}$
					-	$\frac{3 x^{2}}{2}$	+	$0 x$
					+	$\frac{3 x^{2}}{2}$	+	$\frac{9 x}{4}$
							+	$\frac{9 x}{4}$	+	$0$

Step 2.12

Divide the highest order term in the dividend $\frac{9 x}{4}$ by the highest order term in divisor $2 x$ .

				$\frac{x^{2}}{2}$	-	$\frac{3 x}{4}$	+	$\frac{9}{8}$
$2 x$	+	$3$		$x^{3}$	+	$0 x^{2}$	+	$0 x$	+	$0$
			-	$x^{3}$	-	$\frac{3 x^{2}}{2}$
					-	$\frac{3 x^{2}}{2}$	+	$0 x$
					+	$\frac{3 x^{2}}{2}$	+	$\frac{9 x}{4}$
							+	$\frac{9 x}{4}$	+	$0$

Step 2.13

Multiply the new quotient term by the divisor.

				$\frac{x^{2}}{2}$	-	$\frac{3 x}{4}$	+	$\frac{9}{8}$
$2 x$	+	$3$		$x^{3}$	+	$0 x^{2}$	+	$0 x$	+	$0$
			-	$x^{3}$	-	$\frac{3 x^{2}}{2}$
					-	$\frac{3 x^{2}}{2}$	+	$0 x$
					+	$\frac{3 x^{2}}{2}$	+	$\frac{9 x}{4}$
							+	$\frac{9 x}{4}$	+	$0$
							+	$\frac{9 x}{4}$	+	$\frac{27}{8}$

Step 2.14

The expression needs to be subtracted from the dividend, so change all the signs in $\frac{9 x}{4} + \frac{27}{8}$

				$\frac{x^{2}}{2}$	-	$\frac{3 x}{4}$	+	$\frac{9}{8}$
$2 x$	+	$3$		$x^{3}$	+	$0 x^{2}$	+	$0 x$	+	$0$
			-	$x^{3}$	-	$\frac{3 x^{2}}{2}$
					-	$\frac{3 x^{2}}{2}$	+	$0 x$
					+	$\frac{3 x^{2}}{2}$	+	$\frac{9 x}{4}$
							+	$\frac{9 x}{4}$	+	$0$
							-	$\frac{9 x}{4}$	-	$\frac{27}{8}$

Step 2.15

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

				$\frac{x^{2}}{2}$	-	$\frac{3 x}{4}$	+	$\frac{9}{8}$
$2 x$	+	$3$		$x^{3}$	+	$0 x^{2}$	+	$0 x$	+	$0$
			-	$x^{3}$	-	$\frac{3 x^{2}}{2}$
					-	$\frac{3 x^{2}}{2}$	+	$0 x$
					+	$\frac{3 x^{2}}{2}$	+	$\frac{9 x}{4}$
							+	$\frac{9 x}{4}$	+	$0$
							-	$\frac{9 x}{4}$	-	$\frac{27}{8}$
									-	$\frac{27}{8}$

Step 2.16

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

$4 \int \frac{x^{2}}{2} - \frac{3 x}{4} + \frac{9}{8} - \frac{27}{8 (2 x + 3)} d x$

Step 3

Split the single integral into multiple integrals.

$4 (\int \frac{x^{2}}{2} d x + \int - \frac{3 x}{4} d x + \int \frac{9}{8} d x + \int - \frac{27}{8 (2 x + 3)} d x)$

Step 4

Since $\frac{1}{2}$ is constant with respect to $x$ , move $\frac{1}{2}$ out of the integral.

$4 (\frac{1}{2} \int x^{2} d x + \int - \frac{3 x}{4} d x + \int \frac{9}{8} d x + \int - \frac{27}{8 (2 x + 3)} d x)$

Step 5

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

$4 (\frac{1}{2} (\frac{1}{3} x^{3} + C) + \int - \frac{3 x}{4} d x + \int \frac{9}{8} d x + \int - \frac{27}{8 (2 x + 3)} d x)$

Step 6

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

$4 (\frac{1}{2} (\frac{x^{3}}{3} + C) + \int - \frac{3 x}{4} d x + \int \frac{9}{8} d x + \int - \frac{27}{8 (2 x + 3)} d x)$

Step 7

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

$4 (\frac{1}{2} (\frac{x^{3}}{3} + C) - \int \frac{3 x}{4} d x + \int \frac{9}{8} d x + \int - \frac{27}{8 (2 x + 3)} d x)$

Step 8

Since $\frac{3}{4}$ is constant with respect to $x$ , move $\frac{3}{4}$ out of the integral.

$4 (\frac{1}{2} (\frac{x^{3}}{3} + C) - (\frac{3}{4} \int x d x) + \int \frac{9}{8} d x + \int - \frac{27}{8 (2 x + 3)} d x)$

Step 9

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

$4 (\frac{1}{2} (\frac{x^{3}}{3} + C) - \frac{3}{4} (\frac{1}{2} x^{2} + C) + \int \frac{9}{8} d x + \int - \frac{27}{8 (2 x + 3)} d x)$

Step 10

Combine $\frac{1}{2}$ and $x^{2}$ .

$4 (\frac{1}{2} (\frac{x^{3}}{3} + C) - \frac{3}{4} (\frac{x^{2}}{2} + C) + \int \frac{9}{8} d x + \int - \frac{27}{8 (2 x + 3)} d x)$

Step 11

Apply the constant rule.

$4 (\frac{1}{2} (\frac{x^{3}}{3} + C) - \frac{3}{4} (\frac{x^{2}}{2} + C) + \frac{9}{8} x + C + \int - \frac{27}{8 (2 x + 3)} d x)$

Step 12

Combine $\frac{9}{8}$ and $x$ .

$4 (\frac{1}{2} (\frac{x^{3}}{3} + C) - \frac{3}{4} (\frac{x^{2}}{2} + C) + \frac{9 x}{8} + C + \int - \frac{27}{8 (2 x + 3)} d x)$

Step 13

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

$4 (\frac{1}{2} (\frac{x^{3}}{3} + C) - \frac{3}{4} (\frac{x^{2}}{2} + C) + \frac{9 x}{8} + C - \int \frac{27}{8 (2 x + 3)} d x)$

Step 14

Since $\frac{27}{8}$ is constant with respect to $x$ , move $\frac{27}{8}$ out of the integral.

$4 (\frac{1}{2} (\frac{x^{3}}{3} + C) - \frac{3}{4} (\frac{x^{2}}{2} + C) + \frac{9 x}{8} + C - (\frac{27}{8} \int \frac{1}{2 x + 3} d x))$

Step 15

Let $u = 2 x + 3$ . Then $d u = 2 d x$ , so $\frac{1}{2} d u = d x$ . Rewrite using $u$ and $d$ $u$ .

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Step 15.1

Let $u = 2 x + 3$ . Find $\frac{d u}{d x}$ .

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Step 15.1.1

Differentiate $2 x + 3$ .

$\frac{d}{d x} [2 x + 3]$

Step 15.1.2

By the Sum Rule, the derivative of $2 x + 3$ with respect to $x$ is $\frac{d}{d x} [2 x] + \frac{d}{d x} [3]$ .

$\frac{d}{d x} [2 x] + \frac{d}{d x} [3]$

Step 15.1.3

Evaluate $\frac{d}{d x} [2 x]$ .

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Step 15.1.3.1

Since $2$ is constant with respect to $x$ , the derivative of $2 x$ with respect to $x$ is $2 \frac{d}{d x} [x]$ .

$2 \frac{d}{d x} [x] + \frac{d}{d x} [3]$

Step 15.1.3.2

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

$2 \cdot 1 + \frac{d}{d x} [3]$

Step 15.1.3.3

Multiply $2$ by $1$ .

$2 + \frac{d}{d x} [3]$

Step 15.1.4

Differentiate using the Constant Rule.

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Step 15.1.4.1

Since $3$ is constant with respect to $x$ , the derivative of $3$ with respect to $x$ is $0$ .

$2 + 0$

Step 15.1.4.2

Add $2$ and $0$ .

$2$

Step 15.2

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

$4 (\frac{1}{2} (\frac{x^{3}}{3} + C) - \frac{3}{4} (\frac{x^{2}}{2} + C) + \frac{9 x}{8} + C - \frac{27}{8} \int \frac{1}{u} \cdot \frac{1}{2} d u)$

Step 16

Simplify.

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Step 16.1

Multiply $\frac{1}{u}$ by $\frac{1}{2}$ .

$4 (\frac{1}{2} (\frac{x^{3}}{3} + C) - \frac{3}{4} (\frac{x^{2}}{2} + C) + \frac{9 x}{8} + C - \frac{27}{8} \int \frac{1}{u \cdot 2} d u)$

Step 16.2

Move $2$ to the left of $u$ .

$4 (\frac{1}{2} (\frac{x^{3}}{3} + C) - \frac{3}{4} (\frac{x^{2}}{2} + C) + \frac{9 x}{8} + C - \frac{27}{8} \int \frac{1}{2 u} d u)$

Step 17

Since $\frac{1}{2}$ is constant with respect to $u$ , move $\frac{1}{2}$ out of the integral.

$4 (\frac{1}{2} (\frac{x^{3}}{3} + C) - \frac{3}{4} (\frac{x^{2}}{2} + C) + \frac{9 x}{8} + C - \frac{27}{8} (\frac{1}{2} \int \frac{1}{u} d u))$

Step 18

Simplify.

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Step 18.1

Multiply $\frac{1}{2}$ by $\frac{27}{8}$ .

$4 (\frac{1}{2} (\frac{x^{3}}{3} + C) - \frac{3}{4} (\frac{x^{2}}{2} + C) + \frac{9 x}{8} + C - \frac{27}{2 \cdot 8} \int \frac{1}{u} d u)$

Step 18.2

Multiply $2$ by $8$ .

$4 (\frac{1}{2} (\frac{x^{3}}{3} + C) - \frac{3}{4} (\frac{x^{2}}{2} + C) + \frac{9 x}{8} + C - \frac{27}{16} \int \frac{1}{u} d u)$

Step 19

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

$4 (\frac{1}{2} (\frac{x^{3}}{3} + C) - \frac{3}{4} (\frac{x^{2}}{2} + C) + \frac{9 x}{8} + C - \frac{27}{16} (\ln (| u |) + C))$

Step 20

Simplify.

$4 (\frac{x^{3}}{6} - \frac{3 x^{2}}{8} + \frac{9 x}{8} - \frac{27 \ln (| u |)}{16}) + C$

Step 21

Replace all occurrences of $u$ with $2 x + 3$ .

$4 (\frac{x^{3}}{6} - \frac{3 x^{2}}{8} + \frac{9 x}{8} - \frac{27 \ln (| 2 x + 3 |)}{16}) + C$

Step 22

Simplify.

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Step 22.1

To write $\frac{x^{3}}{6}$ as a fraction with a common denominator, multiply by $\frac{8}{8}$ .

$4 (- \frac{3 x^{2}}{8} + \frac{9 x}{8} + \frac{x^{3}}{6} \cdot \frac{8}{8} - \frac{27 \ln (| 2 x + 3 |)}{16}) + C$

Step 22.2

To write $- \frac{27 \ln (| 2 x + 3 |)}{16}$ as a fraction with a common denominator, multiply by $\frac{3}{3}$ .

$4 (- \frac{3 x^{2}}{8} + \frac{9 x}{8} + \frac{x^{3}}{6} \cdot \frac{8}{8} - \frac{27 \ln (| 2 x + 3 |)}{16} \cdot \frac{3}{3}) + C$

Step 22.3

Write each expression with a common denominator of $48$ , by multiplying each by an appropriate factor of $1$ .

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Step 22.3.1

Multiply $\frac{x^{3}}{6}$ by $\frac{8}{8}$ .

$4 (- \frac{3 x^{2}}{8} + \frac{9 x}{8} + \frac{x^{3} \cdot 8}{6 \cdot 8} - \frac{27 \ln (| 2 x + 3 |)}{16} \cdot \frac{3}{3}) + C$

Step 22.3.2

Multiply $6$ by $8$ .

$4 (- \frac{3 x^{2}}{8} + \frac{9 x}{8} + \frac{x^{3} \cdot 8}{48} - \frac{27 \ln (| 2 x + 3 |)}{16} \cdot \frac{3}{3}) + C$

Step 22.3.3

Multiply $\frac{27 \ln (| 2 x + 3 |)}{16}$ by $\frac{3}{3}$ .

$4 (- \frac{3 x^{2}}{8} + \frac{9 x}{8} + \frac{x^{3} \cdot 8}{48} - \frac{27 \ln (| 2 x + 3 |) \cdot 3}{16 \cdot 3}) + C$

Step 22.3.4

Multiply $16$ by $3$ .

$4 (- \frac{3 x^{2}}{8} + \frac{9 x}{8} + \frac{x^{3} \cdot 8}{48} - \frac{27 \ln (| 2 x + 3 |) \cdot 3}{48}) + C$

Step 22.4

Combine the numerators over the common denominator.

$4 (- \frac{3 x^{2}}{8} + \frac{9 x}{8} + \frac{x^{3} \cdot 8 - 27 \ln (| 2 x + 3 |) \cdot 3}{48}) + C$

Step 22.5

Simplify the numerator.

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Step 22.5.1

Move $8$ to the left of $x^{3}$ .

$4 (- \frac{3 x^{2}}{8} + \frac{9 x}{8} + \frac{8 \cdot x^{3} - 27 \ln (| 2 x + 3 |) \cdot 3}{48}) + C$

Step 22.5.2

Multiply $3$ by $- 27$ .

$4 (- \frac{3 x^{2}}{8} + \frac{9 x}{8} + \frac{8 x^{3} - 81 \ln (| 2 x + 3 |)}{48}) + C$

Step 22.6

Apply the distributive property.

$4 (- \frac{3 x^{2}}{8}) + 4 \frac{9 x}{8} + 4 \frac{8 x^{3} - 81 \ln (| 2 x + 3 |)}{48} + C$

Step 22.7

Simplify.

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Step 22.7.1

Cancel the common factor of $4$ .

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Step 22.7.1.1

Move the leading negative in $- \frac{3 x^{2}}{8}$ into the numerator.

$4 \frac{- 3 x^{2}}{8} + 4 \frac{9 x}{8} + 4 \frac{8 x^{3} - 81 \ln (| 2 x + 3 |)}{48} + C$

Step 22.7.1.2

Factor $4$ out of $8$ .

$4 \frac{- 3 x^{2}}{4 (2)} + 4 \frac{9 x}{8} + 4 \frac{8 x^{3} - 81 \ln (| 2 x + 3 |)}{48} + C$

Step 22.7.1.3

Cancel the common factor.

$4 \frac{- 3 x^{2}}{4 \cdot 2} + 4 \frac{9 x}{8} + 4 \frac{8 x^{3} - 81 \ln (| 2 x + 3 |)}{48} + C$

Step 22.7.1.4

Rewrite the expression.

$\frac{- 3 x^{2}}{2} + 4 \frac{9 x}{8} + 4 \frac{8 x^{3} - 81 \ln (| 2 x + 3 |)}{48} + C$

Step 22.7.2

Cancel the common factor of $4$ .

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Step 22.7.2.1

Factor $4$ out of $8$ .

$\frac{- 3 x^{2}}{2} + 4 \frac{9 x}{4 (2)} + 4 \frac{8 x^{3} - 81 \ln (| 2 x + 3 |)}{48} + C$

Step 22.7.2.2

Cancel the common factor.

$\frac{- 3 x^{2}}{2} + 4 \frac{9 x}{4 \cdot 2} + 4 \frac{8 x^{3} - 81 \ln (| 2 x + 3 |)}{48} + C$

Step 22.7.2.3

Rewrite the expression.

$\frac{- 3 x^{2}}{2} + \frac{9 x}{2} + 4 \frac{8 x^{3} - 81 \ln (| 2 x + 3 |)}{48} + C$

Step 22.7.3

Cancel the common factor of $4$ .

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Step 22.7.3.1

Factor $4$ out of $48$ .

$\frac{- 3 x^{2}}{2} + \frac{9 x}{2} + 4 \frac{8 x^{3} - 81 \ln (| 2 x + 3 |)}{4 (12)} + C$

Step 22.7.3.2

Cancel the common factor.

$\frac{- 3 x^{2}}{2} + \frac{9 x}{2} + 4 \frac{8 x^{3} - 81 \ln (| 2 x + 3 |)}{4 \cdot 12} + C$

Step 22.7.3.3

Rewrite the expression.

$\frac{- 3 x^{2}}{2} + \frac{9 x}{2} + \frac{8 x^{3} - 81 \ln (| 2 x + 3 |)}{12} + C$

Step 22.8

Move the negative in front of the fraction.

$- \frac{3 x^{2}}{2} + \frac{9 x}{2} + \frac{8 x^{3} - 81 \ln (| 2 x + 3 |)}{12} + C$

Step 23

Reorder terms.

$- \frac{3}{2} x^{2} + \frac{9}{2} x + \frac{1}{12} (8 x^{3} - 81 \ln (| 2 x + 3 |)) + C$