Answer
1. substitution: $u=x^{2}+4$
then
2. Power Rule
Work Step by Step
The derivative of $(x^{2}+x)$ is $x, $which is in the numerator...
1. we substitute
$\left[\begin{array}{ll}
u=x^{2}+4, & \\
du=2xdx & xdx=\frac{1}{2}du
\end{array}\right]$
after which the integral takes the form
$\displaystyle \frac{1}{2}\int\frac{1}{u^{3}}du=\frac{1}{2}\int u^{-3}du$,
2. we recognize the form $\displaystyle \int x^{n}dx$
which is solved by using the Power Rule.
