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Math Help - need to prove this cross product

  1. #1
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    need 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)
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  2. #2
    MHF Contributor

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    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.
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  3. #3
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    i just get confused by proofs, atleast now i can go through and kinda see whats going on, thanks.
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