Calculus Examples

$\int \frac{3}{x \ln (x)} d x$

Step 1

Since $3$ is constant with respect to $x$ , move $3$ out of the integral.

$3 \int \frac{1}{x \ln (x)} d x$

Step 2

Let $u = \ln (x)$ . Then $d u = \frac{1}{x} d x$ , so $x d u = d x$ . Rewrite using $u$ and $d$ $u$ .

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Step 2.1

Let $u = \ln (x)$ . Find $\frac{d u}{d x}$ .

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Step 2.1.1

Differentiate $\ln (x)$ .

$\frac{d}{d x} [\ln (x)]$

Step 2.1.2

The derivative of $\ln (x)$ with respect to $x$ is $\frac{1}{x}$ .

$\frac{1}{x}$

Step 2.2

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

$3 \int \frac{1}{u} d u$

Step 3

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

$3 (\ln (| u |) + C)$

Step 4

Simplify.

$3 \ln (| u |) + C$

Step 5

Replace all occurrences of $u$ with $\ln (x)$ .

$3 \ln (| \ln (x) |) + C$