Question:
Evaluate the following integrals:
$\int \frac{\log x^{2}}{x} d x$
Solution:
Assume $\log x=t$
$\Rightarrow \mathrm{d}(\log \mathrm{x})=\mathrm{dt}$
$\Rightarrow \frac{1}{\mathrm{x}} \mathrm{dx}=\mathrm{dt}$
Substituting the values oft and dt we get
$\Rightarrow \int \mathrm{t}^{2} \mathrm{dt}$
$\Rightarrow \frac{\mathrm{t}^{3}}{3}+\mathrm{c}$
But $t=\log x$
$\Rightarrow \frac{\log ^{3} x}{3}+c$