# Math Help - Change of variables problem

1. ## Change of variables problem

I'm currently stuck on the following problem: Using a change of variables but without evaulating the integral, show that:
$\int_{1}^{\infty}\frac{lnx}{x^2 } dx = - \int_{0}^{1}lnx dx$
I've tried all sorts of substituions (lnx, lnx/x, lnx/x^2, 1/x^2) but nothing seems to give the desired result. Could somebody please give me a hint?

Many Thanks

2. substitution $x=\dfrac1t$ will solve the problem.

3. [duplicate post]

Try $\frac{1}{x}$.