Calculus Examples

$\int x^{2} \cdot \cos (x) d x$

Step 1

Integrate by parts using the formula $\int u d v = u v - \int v d u$ , where $u = x^{2}$ and $d v = \cos (x)$ .

$x^{2} \sin (x) - \int \sin (x) (2 x) d x$

Step 2

Since $2$ is constant with respect to $x$ , move $2$ out of the integral.

$x^{2} \sin (x) - (2 \int \sin (x) (x) d x)$

Step 3

Multiply $2$ by $- 1$ .

$x^{2} \sin (x) - 2 \int \sin (x) (x) d x$

Step 4

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

$x^{2} \sin (x) - 2 (x (- \cos (x)) - \int - \cos (x) d x)$

Step 5

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

$x^{2} \sin (x) - 2 (x (- \cos (x)) - - \int \cos (x) d x)$

Step 6

Simplify.

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Step 6.1

Multiply $- 1$ by $- 1$ .

$x^{2} \sin (x) - 2 (x (- \cos (x)) + 1 \int \cos (x) d x)$

Step 6.2

Multiply $\int \cos (x) d x$ by $1$ .

$x^{2} \sin (x) - 2 (x (- \cos (x)) + \int \cos (x) d x)$

Step 7

The integral of $\cos (x)$ with respect to $x$ is $\sin (x)$ .

$x^{2} \sin (x) - 2 (x (- \cos (x)) + \sin (x) + C)$

Step 8

Rewrite $x^{2} \sin (x) - 2 (x (- \cos (x)) + \sin (x) + C)$ as $x^{2} \sin (x) - 2 (- x \cos (x) + \sin (x)) + C$ .

$x^{2} \sin (x) - 2 (- x \cos (x) + \sin (x)) + C$