Answer
1. Substitution: $u=x^{2}+4$
then
2. Log Rule
Work Step by Step
The derivative of $(x^{2}+4)$ 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
$\displaystyle \frac{1}{2}\int\frac{1}{u}du$
2. The form $\displaystyle \int\frac{1}{u}du$ is solved by applying the
Log Rule
