Calculus Examples

$\int x \ln (4 x) d x$

Step 1

Integrate by parts using the formula $\int u d v = u v - \int v d u$ , where $u = \ln (4 x)$ and $d v = x$ .

$\ln (4 x) (\frac{1}{2} x^{2}) - \int \frac{1}{2} x^{2} \frac{1}{x} d x$

Step 2

Simplify.

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Step 2.1

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

$\ln (4 x) \frac{x^{2}}{2} - \int \frac{1}{2} x^{2} \frac{1}{x} d x$

Step 2.2

Combine $\ln (4 x)$ and $\frac{x^{2}}{2}$ .

$\frac{\ln (4 x) x^{2}}{2} - \int \frac{1}{2} x^{2} \frac{1}{x} d x$

Step 3

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

$\frac{\ln (4 x) x^{2}}{2} - (\frac{1}{2} \int x^{2} \frac{1}{x} d x)$

Step 4

Simplify.

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Step 4.1

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

$\frac{\ln (4 x) x^{2}}{2} - (\frac{1}{2} \int \frac{x^{2}}{x} d x)$

Step 4.2

Cancel the common factor of $x^{2}$ and $x$ .

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Step 4.2.1

Factor $x$ out of $x^{2}$ .

$\frac{\ln (4 x) x^{2}}{2} - (\frac{1}{2} \int \frac{x \cdot x}{x} d x)$

Step 4.2.2

Cancel the common factors.

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Step 4.2.2.1

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

$\frac{\ln (4 x) x^{2}}{2} - (\frac{1}{2} \int \frac{x \cdot x}{x^{1}} d x)$

Step 4.2.2.2

Factor $x$ out of $x^{1}$ .

$\frac{\ln (4 x) x^{2}}{2} - (\frac{1}{2} \int \frac{x \cdot x}{x \cdot 1} d x)$

Step 4.2.2.3

Cancel the common factor.

$\frac{\ln (4 x) x^{2}}{2} - (\frac{1}{2} \int \frac{x \cdot x}{x \cdot 1} d x)$

Step 4.2.2.4

Rewrite the expression.

$\frac{\ln (4 x) x^{2}}{2} - (\frac{1}{2} \int \frac{x}{1} d x)$

Step 4.2.2.5

Divide $x$ by $1$ .

$\frac{\ln (4 x) x^{2}}{2} - (\frac{1}{2} \int x d x)$

$\frac{\ln (4 x) x^{2}}{2} - \frac{1}{2} \int x d x$

Step 5

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

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

Step 6

Simplify the answer.

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Step 6.1

Rewrite $\frac{\ln (4 x) x^{2}}{2} - \frac{1}{2} (\frac{1}{2} x^{2} + C)$ as $\frac{1}{2} \ln (4 x) x^{2} - \frac{1}{2} \cdot \frac{1}{2} x^{2} + C$ .

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

Step 6.2

Simplify.

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Step 6.2.1

Combine $\frac{1}{2}$ and $\ln (4 x)$ .

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

Step 6.2.2

Combine $\frac{\ln (4 x)}{2}$ and $x^{2}$ .

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

Step 6.2.3

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

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

Step 6.2.4

Multiply $2$ by $2$ .

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

Step 6.3

Combine $x^{2}$ and $\frac{1}{4}$ .

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

Step 6.4

Reorder terms.

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