need to prove this cross product

**rcmango** · February 24th 2009, 11:32 AM

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)

**Plato** · February 24th 2009, 12:10 PM

Just apply basic properties that you are supposed to know.
$u \times \left( {a + b} \right) = \left( {u \times a} \right) + \left( {u \times b} \right)$ .
Let $u=a-b$ and apply again.

**rcmango** · February 24th 2009, 12:24 PM

i just get confused by proofs, atleast now i can go through and kinda see whats going on, thanks.

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