Practise difference-of-squares forms

$\int\frac1{x^2-1}\,dx=\frac12\ln\left|\frac{x-1}{x+1}\right|+C$, on intervals avoiding $x=\pm1$.

$\int\frac1{16-x^2}\,dx=\frac18\ln\left|\frac{4+x}{4-x}\right|+C$, on intervals avoiding $x=\pm4$.