Calculus Examples

$\int x \sqrt[4]{5 x + 1} d x$

Step 1

Integrate by parts using the formula $\int u d v = u v - \int v d u$ , where $u = x$ and $d v = \sqrt[4]{5 x + 1}$ .

$x (\frac{4}{25} {(5 x + 1)}^{\frac{5}{4}}) - \int \frac{4}{25} {(5 x + 1)}^{\frac{5}{4}} d x$

Step 2

Simplify.

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Step 2.1

Combine $\frac{4}{25}$ and ${(5 x + 1)}^{\frac{5}{4}}$ .

$x \frac{4 {(5 x + 1)}^{\frac{5}{4}}}{25} - \int \frac{4}{25} {(5 x + 1)}^{\frac{5}{4}} d x$

Step 2.2

Combine $x$ and $\frac{4 {(5 x + 1)}^{\frac{5}{4}}}{25}$ .

$\frac{x (4 {(5 x + 1)}^{\frac{5}{4}})}{25} - \int \frac{4}{25} {(5 x + 1)}^{\frac{5}{4}} d x$

Step 3

Since $\frac{4}{25}$ is constant with respect to $x$ , move $\frac{4}{25}$ out of the integral.

$\frac{x (4 {(5 x + 1)}^{\frac{5}{4}})}{25} - (\frac{4}{25} \int {(5 x + 1)}^{\frac{5}{4}} d x)$

Step 4

Let $u = 5 x + 1$ . Then $d u = 5 d x$ , so $\frac{1}{5} d u = d x$ . Rewrite using $u$ and $d$ $u$ .

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Step 4.1

Let $u = 5 x + 1$ . Find $\frac{d u}{d x}$ .

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Step 4.1.1

Differentiate $5 x + 1$ .

$\frac{d}{d x} [5 x + 1]$

Step 4.1.2

By the Sum Rule, the derivative of $5 x + 1$ with respect to $x$ is $\frac{d}{d x} [5 x] + \frac{d}{d x} [1]$ .

$\frac{d}{d x} [5 x] + \frac{d}{d x} [1]$

Step 4.1.3

Evaluate $\frac{d}{d x} [5 x]$ .

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Step 4.1.3.1

Since $5$ is constant with respect to $x$ , the derivative of $5 x$ with respect to $x$ is $5 \frac{d}{d x} [x]$ .

$5 \frac{d}{d x} [x] + \frac{d}{d x} [1]$

Step 4.1.3.2

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

$5 \cdot 1 + \frac{d}{d x} [1]$

Step 4.1.3.3

Multiply $5$ by $1$ .

$5 + \frac{d}{d x} [1]$

Step 4.1.4

Differentiate using the Constant Rule.

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Step 4.1.4.1

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

$5 + 0$

Step 4.1.4.2

Add $5$ and $0$ .

$5$

Step 4.2

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

$\frac{x (4 {(5 x + 1)}^{\frac{5}{4}})}{25} - \frac{4}{25} \int u^{\frac{5}{4}} \frac{1}{5} d u$

Step 5

Combine $u^{\frac{5}{4}}$ and $\frac{1}{5}$ .

$\frac{x (4 {(5 x + 1)}^{\frac{5}{4}})}{25} - \frac{4}{25} \int \frac{u^{\frac{5}{4}}}{5} d u$

Step 6

Since $\frac{1}{5}$ is constant with respect to $u$ , move $\frac{1}{5}$ out of the integral.

$\frac{x (4 {(5 x + 1)}^{\frac{5}{4}})}{25} - \frac{4}{25} (\frac{1}{5} \int u^{\frac{5}{4}} d u)$

Step 7

Simplify.

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Step 7.1

Multiply $\frac{1}{5}$ by $\frac{4}{25}$ .

$\frac{x (4 {(5 x + 1)}^{\frac{5}{4}})}{25} - \frac{4}{5 \cdot 25} \int u^{\frac{5}{4}} d u$

Step 7.2

Multiply $5$ by $25$ .

$\frac{x (4 {(5 x + 1)}^{\frac{5}{4}})}{25} - \frac{4}{125} \int u^{\frac{5}{4}} d u$

Step 8

By the Power Rule, the integral of $u^{\frac{5}{4}}$ with respect to $u$ is $\frac{4}{9} u^{\frac{9}{4}}$ .

$\frac{x (4 {(5 x + 1)}^{\frac{5}{4}})}{25} - \frac{4}{125} (\frac{4}{9} u^{\frac{9}{4}} + C)$

Step 9

Simplify.

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Step 9.1

Rewrite $\frac{x (4 {(5 x + 1)}^{\frac{5}{4}})}{25} - \frac{4}{125} (\frac{4}{9} u^{\frac{9}{4}} + C)$ as $\frac{4}{25} x {(5 x + 1)}^{\frac{5}{4}} - \frac{4}{125} \cdot \frac{4}{9} u^{\frac{9}{4}} + C$ .

$\frac{4}{25} x {(5 x + 1)}^{\frac{5}{4}} - \frac{4}{125} \cdot \frac{4}{9} u^{\frac{9}{4}} + C$

Step 9.2

Simplify.

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Step 9.2.1

Combine $\frac{4}{25}$ and $x$ .

$\frac{4 x}{25} {(5 x + 1)}^{\frac{5}{4}} - \frac{4}{125} \cdot \frac{4}{9} u^{\frac{9}{4}} + C$

Step 9.2.2

Combine $\frac{4 x}{25}$ and ${(5 x + 1)}^{\frac{5}{4}}$ .

$\frac{4 x {(5 x + 1)}^{\frac{5}{4}}}{25} - \frac{4}{125} \cdot \frac{4}{9} u^{\frac{9}{4}} + C$

Step 9.2.3

Multiply $\frac{4}{9}$ by $\frac{4}{125}$ .

$\frac{4 x {(5 x + 1)}^{\frac{5}{4}}}{25} - \frac{4 \cdot 4}{9 \cdot 125} u^{\frac{9}{4}} + C$

Step 9.2.4

Multiply $4$ by $4$ .

$\frac{4 x {(5 x + 1)}^{\frac{5}{4}}}{25} - \frac{16}{9 \cdot 125} u^{\frac{9}{4}} + C$

Step 9.2.5

Multiply $9$ by $125$ .

$\frac{4 x {(5 x + 1)}^{\frac{5}{4}}}{25} - \frac{16}{1125} u^{\frac{9}{4}} + C$

Step 9.2.6

To write $- \frac{16}{1125} u^{\frac{9}{4}}$ as a fraction with a common denominator, multiply by $\frac{25}{25}$ .

$\frac{4 x {(5 x + 1)}^{\frac{5}{4}}}{25} - \frac{16}{1125} u^{\frac{9}{4}} \cdot \frac{25}{25} + C$

Step 9.2.7

Combine $- \frac{16}{1125} u^{\frac{9}{4}}$ and $\frac{25}{25}$ .

$\frac{4 x {(5 x + 1)}^{\frac{5}{4}}}{25} + \frac{- \frac{16}{1125} u^{\frac{9}{4}} \cdot 25}{25} + C$

Step 9.2.8

Combine the numerators over the common denominator.

$\frac{4 x {(5 x + 1)}^{\frac{5}{4}} - \frac{16}{1125} u^{\frac{9}{4}} \cdot 25}{25} + C$

Step 9.2.9

Combine $u^{\frac{9}{4}}$ and $\frac{16}{1125}$ .

$\frac{4 x {(5 x + 1)}^{\frac{5}{4}} - \frac{u^{\frac{9}{4}} \cdot 16}{1125} \cdot 25}{25} + C$

Step 9.2.10

Multiply $25$ by $- 1$ .

$\frac{4 x {(5 x + 1)}^{\frac{5}{4}} - 25 \frac{u^{\frac{9}{4}} \cdot 16}{1125}}{25} + C$

Step 9.2.11

Combine $- 25$ and $\frac{u^{\frac{9}{4}} \cdot 16}{1125}$ .

$\frac{4 x {(5 x + 1)}^{\frac{5}{4}} + \frac{- 25 (u^{\frac{9}{4}} \cdot 16)}{1125}}{25} + C$

Step 9.2.12

Multiply $16$ by $- 25$ .

$\frac{4 x {(5 x + 1)}^{\frac{5}{4}} + \frac{- 400 u^{\frac{9}{4}}}{1125}}{25} + C$

Step 9.2.13

Factor $25$ out of $- 400 u^{\frac{9}{4}}$ .

$\frac{4 x {(5 x + 1)}^{\frac{5}{4}} + \frac{25 (- 16 u^{\frac{9}{4}})}{1125}}{25} + C$

Step 9.2.14

Cancel the common factors.

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Step 9.2.14.1

Factor $25$ out of $1125$ .

$\frac{4 x {(5 x + 1)}^{\frac{5}{4}} + \frac{25 (- 16 u^{\frac{9}{4}})}{25 (45)}}{25} + C$

Step 9.2.14.2

Cancel the common factor.

$\frac{4 x {(5 x + 1)}^{\frac{5}{4}} + \frac{25 (- 16 u^{\frac{9}{4}})}{25 \cdot 45}}{25} + C$

Step 9.2.14.3

Rewrite the expression.

$\frac{4 x {(5 x + 1)}^{\frac{5}{4}} + \frac{- 16 u^{\frac{9}{4}}}{45}}{25} + C$

Step 9.2.15

Move the negative in front of the fraction.

$\frac{4 x {(5 x + 1)}^{\frac{5}{4}} - \frac{16 u^{\frac{9}{4}}}{45}}{25} + C$

Step 9.2.16

To write $4 x {(5 x + 1)}^{\frac{5}{4}}$ as a fraction with a common denominator, multiply by $\frac{45}{45}$ .

$\frac{4 x {(5 x + 1)}^{\frac{5}{4}} \cdot \frac{45}{45} - \frac{16 u^{\frac{9}{4}}}{45}}{25} + C$

Step 9.2.17

Combine $4 x {(5 x + 1)}^{\frac{5}{4}}$ and $\frac{45}{45}$ .

$\frac{\frac{4 x {(5 x + 1)}^{\frac{5}{4}} \cdot 45}{45} - \frac{16 u^{\frac{9}{4}}}{45}}{25} + C$

Step 9.2.18

Combine the numerators over the common denominator.

$\frac{\frac{4 x {(5 x + 1)}^{\frac{5}{4}} \cdot 45 - 16 u^{\frac{9}{4}}}{45}}{25} + C$

Step 9.2.19

Multiply $45$ by $4$ .

$\frac{\frac{180 x {(5 x + 1)}^{\frac{5}{4}} - 16 u^{\frac{9}{4}}}{45}}{25} + C$

Step 9.2.20

Rewrite $\frac{\frac{180 x {(5 x + 1)}^{\frac{5}{4}} - 16 u^{\frac{9}{4}}}{45}}{25}$ as a product.

$\frac{180 x {(5 x + 1)}^{\frac{5}{4}} - 16 u^{\frac{9}{4}}}{45} \cdot \frac{1}{25} + C$

Step 9.2.21

Multiply $\frac{180 x {(5 x + 1)}^{\frac{5}{4}} - 16 u^{\frac{9}{4}}}{45}$ by $\frac{1}{25}$ .

$\frac{180 x {(5 x + 1)}^{\frac{5}{4}} - 16 u^{\frac{9}{4}}}{45 \cdot 25} + C$

Step 9.2.22

Multiply $45$ by $25$ .

$\frac{180 x {(5 x + 1)}^{\frac{5}{4}} - 16 u^{\frac{9}{4}}}{1125} + C$

Step 10

Replace all occurrences of $u$ with $5 x + 1$ .

$\frac{180 x {(5 x + 1)}^{\frac{5}{4}} - 16 {(5 x + 1)}^{\frac{9}{4}}}{1125} + C$

Step 11

Reorder terms.

$\frac{1}{1125} (180 x {(5 x + 1)}^{\frac{5}{4}} - 16 {(5 x + 1)}^{\frac{9}{4}}) + C$