# Why do you Tack on The Negative For this Integral

by bmed90
Tags: integral, negative, tack
 PF Gold P: 1,941 Because using u-substitution, we get this: u = 1 - y, du = - dy And so... $$\int \frac{1}{1-y} dy = - \int \frac{1}{u} du$$ Integrating the right-hand side, we get - ln|u| + C, or - ln|1-y| + C.