integrate 1 / (x^2 - 1)^2

aija

1. The problem statement, all variables and given/known data
integrate dx / (x^2 - 1)^2


2. Relevant equations



3. The attempt at a solution
There is nothing i can substitute to get rid of x. Except x=sqr(t), but then dx is 1/2sqr(t) so i get:

∫( dt / (t-1)^2 * 2sqr(t) )

and it's still impossible to integrate.

arildno

Try partial fractions decomposition, remembering that (x^2-1)=(x+1)(x-1)

Ray Vickson

A more-or-less standard substitution to try out when you see 'x^2-1' is x = cosh(t).