Calculus Examples

$\int x^{2} \sqrt{3 x + 2} d x$

Step 1

Integrate by parts using the formula $\int u d v = u v - \int v d u$ , where $u = x^{2}$ and $d v = \sqrt{3 x + 2}$ .

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

Step 2

Simplify.

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Step 2.1

Combine $\frac{2}{9}$ and ${(3 x + 2)}^{\frac{3}{2}}$ .

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

Step 2.2

Combine $x^{2}$ and $\frac{2 {(3 x + 2)}^{\frac{3}{2}}}{9}$ .

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

Step 3

Since $\frac{2}{9} \cdot 2$ is constant with respect to $x$ , move $\frac{2}{9} \cdot 2$ out of the integral.

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

Step 4

Simplify.

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Step 4.1

Combine $\frac{2}{9}$ and $2$ .

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

Step 4.2

Multiply $2$ by $2$ .

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

Step 5

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

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Step 5.1

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

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Step 5.1.1

Differentiate $3 x + 2$ .

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

Step 5.1.2

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

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

Step 5.1.3

Evaluate $\frac{d}{d x} [3 x]$ .

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Step 5.1.3.1

Since $3$ is constant with respect to $x$ , the derivative of $3 x$ with respect to $x$ is $3 \frac{d}{d x} [x]$ .

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

Step 5.1.3.2

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

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

Step 5.1.3.3

Multiply $3$ by $1$ .

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

Step 5.1.4

Differentiate using the Constant Rule.

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Step 5.1.4.1

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

$3 + 0$

Step 5.1.4.2

Add $3$ and $0$ .

$3$

Step 5.2

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

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

Step 6

Combine $\frac{1}{3}$ and $u^{\frac{3}{2}}$ .

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

Step 7

Simplify.

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Step 7.1

Apply the distributive property.

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

Step 7.2

Reorder $\frac{u^{\frac{3}{2}}}{3}$ and $- 1$ .

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

Step 7.3

Multiply $\frac{u^{\frac{3}{2}}}{3}$ by $\frac{u}{3}$ .

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

Step 7.4

Raise $u$ to the power of $1$ .

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

Step 7.5

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

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

Step 7.6

Write $1$ as a fraction with a common denominator.

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

Step 7.7

Combine the numerators over the common denominator.

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

Step 7.8

Add $3$ and $2$ .

$\frac{x^{2} (2 {(3 x + 2)}^{\frac{3}{2}})}{9} - \frac{4}{9} \int \frac{u^{\frac{5}{2}}}{3 \cdot 3} - 1 \frac{u^{\frac{3}{2}}}{3} \frac{2}{3} d u$

Step 7.9

Multiply $3$ by $3$ .

$\frac{x^{2} (2 {(3 x + 2)}^{\frac{3}{2}})}{9} - \frac{4}{9} \int \frac{u^{\frac{5}{2}}}{9} - 1 \frac{u^{\frac{3}{2}}}{3} \frac{2}{3} d u$

Step 7.10

Combine $- 1 \frac{u^{\frac{3}{2}}}{3}$ and $\frac{2}{3}$ .

$\frac{x^{2} (2 {(3 x + 2)}^{\frac{3}{2}})}{9} - \frac{4}{9} \int \frac{u^{\frac{5}{2}}}{9} + \frac{- 1 \frac{u^{\frac{3}{2}}}{3} \cdot 2}{3} d u$

Step 7.11

Combine $\frac{u^{\frac{3}{2}}}{3}$ and $2$ .

$\frac{x^{2} (2 {(3 x + 2)}^{\frac{3}{2}})}{9} - \frac{4}{9} \int \frac{u^{\frac{5}{2}}}{9} + \frac{- 1 \frac{u^{\frac{3}{2}} \cdot 2}{3}}{3} d u$

Step 8

Simplify.

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Step 8.1

Move $2$ to the left of $u^{\frac{3}{2}}$ .

$\frac{x^{2} (2 {(3 x + 2)}^{\frac{3}{2}})}{9} - \frac{4}{9} \int \frac{u^{\frac{5}{2}}}{9} + \frac{- 1 \frac{2 \cdot u^{\frac{3}{2}}}{3}}{3} d u$

Step 8.2

Rewrite $- 1 \frac{2 u^{\frac{3}{2}}}{3}$ as $- \frac{2 u^{\frac{3}{2}}}{3}$ .

$\frac{x^{2} (2 {(3 x + 2)}^{\frac{3}{2}})}{9} - \frac{4}{9} \int \frac{u^{\frac{5}{2}}}{9} + \frac{- \frac{2 u^{\frac{3}{2}}}{3}}{3} d u$

Step 8.3

Rewrite $\frac{- \frac{2 u^{\frac{3}{2}}}{3}}{3}$ as a product.

$\frac{x^{2} (2 {(3 x + 2)}^{\frac{3}{2}})}{9} - \frac{4}{9} \int \frac{u^{\frac{5}{2}}}{9} - \frac{2 u^{\frac{3}{2}}}{3} \cdot \frac{1}{3} d u$

Step 8.4

Multiply $\frac{1}{3}$ by $\frac{2 u^{\frac{3}{2}}}{3}$ .

$\frac{x^{2} (2 {(3 x + 2)}^{\frac{3}{2}})}{9} - \frac{4}{9} \int \frac{u^{\frac{5}{2}}}{9} - \frac{2 u^{\frac{3}{2}}}{3 \cdot 3} d u$

Step 8.5

Multiply $3$ by $3$ .

$\frac{x^{2} (2 {(3 x + 2)}^{\frac{3}{2}})}{9} - \frac{4}{9} \int \frac{u^{\frac{5}{2}}}{9} - \frac{2 u^{\frac{3}{2}}}{9} d u$

Step 9

Split the single integral into multiple integrals.

$\frac{x^{2} (2 {(3 x + 2)}^{\frac{3}{2}})}{9} - \frac{4}{9} (\int \frac{u^{\frac{5}{2}}}{9} d u + \int - \frac{2 u^{\frac{3}{2}}}{9} d u)$

Step 10

Since $\frac{1}{9}$ is constant with respect to $u$ , move $\frac{1}{9}$ out of the integral.

$\frac{x^{2} (2 {(3 x + 2)}^{\frac{3}{2}})}{9} - \frac{4}{9} (\frac{1}{9} \int u^{\frac{5}{2}} d u + \int - \frac{2 u^{\frac{3}{2}}}{9} d u)$

Step 11

By the Power Rule, the integral of $u^{\frac{5}{2}}$ with respect to $u$ is $\frac{2}{7} u^{\frac{7}{2}}$ .

$\frac{x^{2} (2 {(3 x + 2)}^{\frac{3}{2}})}{9} - \frac{4}{9} (\frac{1}{9} (\frac{2}{7} u^{\frac{7}{2}} + C) + \int - \frac{2 u^{\frac{3}{2}}}{9} d u)$

Step 12

Combine $\frac{2}{7}$ and $u^{\frac{7}{2}}$ .

$\frac{x^{2} (2 {(3 x + 2)}^{\frac{3}{2}})}{9} - \frac{4}{9} (\frac{1}{9} (\frac{2 u^{\frac{7}{2}}}{7} + C) + \int - \frac{2 u^{\frac{3}{2}}}{9} d u)$

Step 13

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

$\frac{x^{2} (2 {(3 x + 2)}^{\frac{3}{2}})}{9} - \frac{4}{9} (\frac{1}{9} (\frac{2 u^{\frac{7}{2}}}{7} + C) - \int \frac{2 u^{\frac{3}{2}}}{9} d u)$

Step 14

Since $\frac{2}{9}$ is constant with respect to $u$ , move $\frac{2}{9}$ out of the integral.

$\frac{x^{2} (2 {(3 x + 2)}^{\frac{3}{2}})}{9} - \frac{4}{9} (\frac{1}{9} (\frac{2 u^{\frac{7}{2}}}{7} + C) - (\frac{2}{9} \int u^{\frac{3}{2}} d u))$

Step 15

By the Power Rule, the integral of $u^{\frac{3}{2}}$ with respect to $u$ is $\frac{2}{5} u^{\frac{5}{2}}$ .

$\frac{x^{2} (2 {(3 x + 2)}^{\frac{3}{2}})}{9} - \frac{4}{9} (\frac{1}{9} (\frac{2 u^{\frac{7}{2}}}{7} + C) - \frac{2}{9} (\frac{2}{5} u^{\frac{5}{2}} + C))$

Step 16

Simplify.

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Step 16.1

Combine $\frac{2}{5}$ and $u^{\frac{5}{2}}$ .

$\frac{x^{2} (2 {(3 x + 2)}^{\frac{3}{2}})}{9} - \frac{4}{9} (\frac{1}{9} (\frac{2 u^{\frac{7}{2}}}{7} + C) - \frac{2}{9} (\frac{2 u^{\frac{5}{2}}}{5} + C))$

Step 16.2

Simplify.

$\frac{2}{9} x^{2} {(3 x + 2)}^{\frac{3}{2}} - \frac{4}{9} (\frac{1}{9} \cdot \frac{2}{7} u^{\frac{7}{2}} - \frac{2}{9} \cdot \frac{2}{5} u^{\frac{5}{2}}) + C$

Step 16.3

Simplify.

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Step 16.3.1

Combine $\frac{2}{9}$ and $x^{2}$ .

$\frac{2 x^{2}}{9} {(3 x + 2)}^{\frac{3}{2}} - \frac{4}{9} (\frac{1}{9} \cdot \frac{2}{7} u^{\frac{7}{2}} - \frac{2}{9} \cdot \frac{2}{5} u^{\frac{5}{2}}) + C$

Step 16.3.2

Combine $\frac{2 x^{2}}{9}$ and ${(3 x + 2)}^{\frac{3}{2}}$ .

$\frac{2 x^{2} {(3 x + 2)}^{\frac{3}{2}}}{9} - \frac{4}{9} (\frac{1}{9} \cdot \frac{2}{7} u^{\frac{7}{2}} - \frac{2}{9} \cdot \frac{2}{5} u^{\frac{5}{2}}) + C$

Step 16.3.3

Multiply $\frac{1}{9}$ by $\frac{2}{7}$ .

$\frac{2 x^{2} {(3 x + 2)}^{\frac{3}{2}}}{9} - \frac{4}{9} (\frac{2}{9 \cdot 7} u^{\frac{7}{2}} - \frac{2}{9} \cdot \frac{2}{5} u^{\frac{5}{2}}) + C$

Step 16.3.4

Multiply $9$ by $7$ .

$\frac{2 x^{2} {(3 x + 2)}^{\frac{3}{2}}}{9} - \frac{4}{9} (\frac{2}{63} u^{\frac{7}{2}} - \frac{2}{9} \cdot \frac{2}{5} u^{\frac{5}{2}}) + C$

Step 16.3.5

Multiply $\frac{2}{5}$ by $\frac{2}{9}$ .

$\frac{2 x^{2} {(3 x + 2)}^{\frac{3}{2}}}{9} - \frac{4}{9} (\frac{2}{63} u^{\frac{7}{2}} - \frac{2 \cdot 2}{5 \cdot 9} u^{\frac{5}{2}}) + C$

Step 16.3.6

Multiply $2$ by $2$ .

$\frac{2 x^{2} {(3 x + 2)}^{\frac{3}{2}}}{9} - \frac{4}{9} (\frac{2}{63} u^{\frac{7}{2}} - \frac{4}{5 \cdot 9} u^{\frac{5}{2}}) + C$

Step 16.3.7

Multiply $5$ by $9$ .

$\frac{2 x^{2} {(3 x + 2)}^{\frac{3}{2}}}{9} - \frac{4}{9} (\frac{2}{63} u^{\frac{7}{2}} - \frac{4}{45} u^{\frac{5}{2}}) + C$

Step 16.3.8

To write $- \frac{4}{9} (\frac{2}{63} u^{\frac{7}{2}} - \frac{4}{45} u^{\frac{5}{2}})$ as a fraction with a common denominator, multiply by $\frac{9}{9}$ .

$\frac{2 x^{2} {(3 x + 2)}^{\frac{3}{2}}}{9} - \frac{4}{9} (\frac{2}{63} u^{\frac{7}{2}} - \frac{4}{45} u^{\frac{5}{2}}) \cdot \frac{9}{9} + C$

Step 16.3.9

Combine $- \frac{4}{9} (\frac{2}{63} u^{\frac{7}{2}} - \frac{4}{45} u^{\frac{5}{2}})$ and $\frac{9}{9}$ .

$\frac{2 x^{2} {(3 x + 2)}^{\frac{3}{2}}}{9} + \frac{- \frac{4}{9} (\frac{2}{63} u^{\frac{7}{2}} - \frac{4}{45} u^{\frac{5}{2}}) \cdot 9}{9} + C$

Step 16.3.10

Combine the numerators over the common denominator.

$\frac{2 x^{2} {(3 x + 2)}^{\frac{3}{2}} - \frac{4}{9} (\frac{2}{63} u^{\frac{7}{2}} - \frac{4}{45} u^{\frac{5}{2}}) \cdot 9}{9} + C$

Step 16.3.11

Combine $\frac{2}{63}$ and $u^{\frac{7}{2}}$ .

$\frac{2 x^{2} {(3 x + 2)}^{\frac{3}{2}} - \frac{4}{9} (\frac{2 u^{\frac{7}{2}}}{63} - \frac{4}{45} u^{\frac{5}{2}}) \cdot 9}{9} + C$

Step 16.3.12

Combine $u^{\frac{5}{2}}$ and $\frac{4}{45}$ .

$\frac{2 x^{2} {(3 x + 2)}^{\frac{3}{2}} - \frac{4}{9} (\frac{2 u^{\frac{7}{2}}}{63} - \frac{u^{\frac{5}{2}} \cdot 4}{45}) \cdot 9}{9} + C$

Step 16.3.13

Multiply $9$ by $- 1$ .

$\frac{2 x^{2} {(3 x + 2)}^{\frac{3}{2}} - 9 (\frac{4}{9}) (\frac{2 u^{\frac{7}{2}}}{63} - \frac{u^{\frac{5}{2}} \cdot 4}{45})}{9} + C$

Step 16.3.14

Combine $- 9$ and $\frac{4}{9}$ .

$\frac{2 x^{2} {(3 x + 2)}^{\frac{3}{2}} + \frac{- 9 \cdot 4}{9} (\frac{2 u^{\frac{7}{2}}}{63} - \frac{u^{\frac{5}{2}} \cdot 4}{45})}{9} + C$

Step 16.3.15

Multiply $- 9$ by $4$ .

$\frac{2 x^{2} {(3 x + 2)}^{\frac{3}{2}} + \frac{- 36}{9} (\frac{2 u^{\frac{7}{2}}}{63} - \frac{u^{\frac{5}{2}} \cdot 4}{45})}{9} + C$

Step 16.3.16

Cancel the common factor of $- 36$ and $9$ .

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Step 16.3.16.1

Factor $9$ out of $- 36$ .

$\frac{2 x^{2} {(3 x + 2)}^{\frac{3}{2}} + \frac{9 \cdot - 4}{9} (\frac{2 u^{\frac{7}{2}}}{63} - \frac{u^{\frac{5}{2}} \cdot 4}{45})}{9} + C$

Step 16.3.16.2

Cancel the common factors.

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Step 16.3.16.2.1

Factor $9$ out of $9$ .

$\frac{2 x^{2} {(3 x + 2)}^{\frac{3}{2}} + \frac{9 \cdot - 4}{9 (1)} (\frac{2 u^{\frac{7}{2}}}{63} - \frac{u^{\frac{5}{2}} \cdot 4}{45})}{9} + C$

Step 16.3.16.2.2

Cancel the common factor.

$\frac{2 x^{2} {(3 x + 2)}^{\frac{3}{2}} + \frac{9 \cdot - 4}{9 \cdot 1} (\frac{2 u^{\frac{7}{2}}}{63} - \frac{u^{\frac{5}{2}} \cdot 4}{45})}{9} + C$

Step 16.3.16.2.3

Rewrite the expression.

$\frac{2 x^{2} {(3 x + 2)}^{\frac{3}{2}} + \frac{- 4}{1} (\frac{2 u^{\frac{7}{2}}}{63} - \frac{u^{\frac{5}{2}} \cdot 4}{45})}{9} + C$

Step 16.3.16.2.4

Divide $- 4$ by $1$ .

$\frac{2 x^{2} {(3 x + 2)}^{\frac{3}{2}} - 4 (\frac{2 u^{\frac{7}{2}}}{63} - \frac{u^{\frac{5}{2}} \cdot 4}{45})}{9} + C$

Step 16.3.17

Move $4$ to the left of $u^{\frac{5}{2}}$ .

$\frac{2 x^{2} {(3 x + 2)}^{\frac{3}{2}} - 4 (\frac{2 u^{\frac{7}{2}}}{63} - \frac{4 u^{\frac{5}{2}}}{45})}{9} + C$

Step 17

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

$\frac{2 x^{2} {(3 x + 2)}^{\frac{3}{2}} - 4 (\frac{2 {(3 x + 2)}^{\frac{7}{2}}}{63} - \frac{4 {(3 x + 2)}^{\frac{5}{2}}}{45})}{9} + C$

Step 18

Reorder terms.

$\frac{1}{9} (2 x^{2} {(3 x + 2)}^{\frac{3}{2}} - 4 (\frac{2}{63} {(3 x + 2)}^{\frac{7}{2}} - \frac{4}{45} {(3 x + 2)}^{\frac{5}{2}})) + C$