Integration method unknown $$
\int \frac{4}{(x+y)^{2}} \,\mathrm{d}y = \frac{-4}{x+y}
$$
How do you get to that answer? I've been looking over my formulas, tried to compute the power and integrate after but no success.

Hint: 
$$\int {(f(y))^n f'(y)dy}=\frac{1}{n+1}f(y)^{n+1}$$
In your case, $f(y)=(x+y)^{-2}$. Can you take it from here?
