Here, we show you a step-by-step solved example of integration by parts. This solution was automatically generated by our smart calculator:
$\int x\cdot\cos\left(x\right)dx$We can solve the integral $\int x\cos\left(x\right)dx$ by applying integration by parts method to calculate the integral of the product of two functions, using the following formula
$\displaystyle\int u\cdot dv=u\cdot v-\int v \cdot du$ Intermediate steps
The derivative of the linear function is equal to $1$
First, identify or choose $u$ and calculate it's derivative, $du$
$\beginNow, identify $dv$ and calculate $v$
$\beginSolve the integral to find $v$
$v=\int\cos\left(x\right)dx$Apply the integral of the cosine function: $\int\cos(x)dx=\sin(x)$
$\sin\left(x\right)$Now replace the values of $u$, $du$ and $v$ in the last formula
$x\sin\left(x\right)-\int\sin\left(x\right)dx$ Intermediate steps
Apply the integral of the sine function: $\int\sin(x)dx=-\cos(x)$
$1\cos\left(x\right)$Any expression multiplied by $1$ is equal to itself
$\cos\left(x\right)$The integral $-\int\sin\left(x\right)dx$ results in: $\cos\left(x\right)$
$\cos\left(x\right)$ Explain this step furtherGather the results of all integrals
$x\sin\left(x\right)+\cos\left(x\right)$As the integral that we are solving is an indefinite integral, when we finish integrating we must add the constant of integration $C$