I tried a simple simplification, namely
FullSimplify[Sqrt[a^2*b^2 - a^4]/a, a > 0 && b > 0 && a < b]
which I thought to be pretty simple, however mathematica does not simplify it in the slightest way. What can I do?
P.S. This is only the first step of large simplifications I will have to do, but if it doesnt work at this level, no way it will do any good on complicated expressions.