Answer
\begin{align*}
\int(\ln x)^{k} d x&=x(\ln x)^{k}-k \int(\ln x)^{k-1} d x
\end{align*}
Work Step by Step
Given $$\int(\ln x)^{k} d x$$
Let
\begin{align*}
u&= (\ln x)^k \ \ \ \ \ \ \ dv=dx\\
du& =\frac{k}{x}(\ln x)^{k-1}\ \ \ \ \ v=x
\end{align*}
Then
\begin{align*}
\int(\ln x)^{k} d x&=x(\ln x)^{k}-k \int(\ln x)^{k-1} d x
\end{align*}