to to show that (a - b) x (a + b) = 2(a x b)

please help me, not sure how to show this one. (cross product)

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- Feb 24th 2009, 11:32 AMrcmangoneed to prove this cross product
to to show that (a - b) x (a + b) = 2(a x b)

please help me, not sure how to show this one. (cross product) - Feb 24th 2009, 12:10 PMPlato
Just apply basic properties that

**you are supposed to know.**

$\displaystyle u \times \left( {a + b} \right) = \left( {u \times a} \right) + \left( {u \times b} \right)$.

Let $\displaystyle u=a-b$ and apply again. - Feb 24th 2009, 12:24 PMrcmango
i just get confused by proofs, atleast now i can go through and kinda see whats going on, thanks.