(a+b)(a-b) = b( a-b). Still don't get THIS step. And I allready said (a-b)=0, but that's not the point anymore!
<img src="/ubbthreads/images/graemlins/idea.gif" alt="" /> Got it <img src="/ubbthreads/images/graemlins/biggrin.gif" alt="" />. a^2-b^2=ab-b^2. Then they break b out, like this: b(a-b), and voila, it works! (And still, (a-b)=0, so it doesn't really work, but otherwise it works fine <img src="/ubbthreads/images/graemlins/biggrin.gif" alt="" />.)
Übereil