# Why do you Tack on The Negative For this Integral

by bmed90
Tags: integral, negative, tack
 P: 83 If you integrate 1/(1-y)dy why do you end up with a negative in front of your answer -ln|1-y|+c
 PF Patron P: 1,930 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.
 P: 83 gotcha

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