I'm looking for patterns and if you can add to things I noticed before working it out, that would be good :-] 1. [tex](a+b+c)(a+b-c)=a^2+b^2+c^2+2ab[/tex] I noticed that b+c and b-c compensated for each other. 2. [tex](a+b+c)(a-b-c)=a^2-b^2-c^2-2bc[/tex] a+b and a-b compensated for each other and the fact that it's b+c and -b-c, is the reason that it was -2bc? 3. [tex](a+b-c)(a-b+c)=a^2-b^2-c^2+2bc[/tex] a+b and a-b compensated for each other, Now I figured from problem 2 that it would be 2bc again, but I didn't predict the sign correctly?