I have a 23 problem assignment due at the end of the week, and although I'm going to have a chance to talk to my teacher about the questions I have, I'd like to go ahead and get going on the problems. I've successfully completed 21 of them, but the last two are stumping me. I'm submitting them here for your help. I really just don't understand!!!(adsbygoogle = window.adsbygoogle || []).push({});

1. split (A+B)x(A+B) into four terms to deduce that (AXB)=-(BXA)

my first thought is that I need to expand them (obviously), but I'm not quite sure exactly what to expand them TO. I have tried making it (A+B)A X (A+B)B, but that yields (A^2+AB) X (AB+B^2) and I'm not sure how much good that does me. If you could just point me in the direction of what to expand, I think I can get it from there.

2. verify B.(AXB)=0

um... I have absolutely no clue as to what to do. do I use arbitrary variables and solve (e.g. use A=<x,y,z>)?

I know this is a lot to ask, but I just want to get ahead on this homework and understand generally what I'm doing before I talk to my teacher.

thanks in advance!

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# Homework Help: Help with cross product proofs

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