Could someone give me a pointer? I've been banging my head against this problem for over an hour. I can't seem to find a way to simplify the left hand side.
Thanks for your help,
Yeah in most of the times although you have to be careful. For example here the identity doesn't hold for because on both sides the denominator would be 0 but when we cross multiplied, the expression we got holds for . The other manipulations were equivalent on the given domain therefore we proved the identity for all s except ( ) which we had to do. So in general you should check the domains.