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Homework Help: Probably easy proof for you guys

  1. Jan 21, 2010 #1
    1. The problem statement, all variables and given/known data

    Prove if [tex]\vec{x}\times\vec{v}=\vec{x}\times \vec{u}[/tex], then [tex]\vec{v}=\vec{u}[/tex]
    where [tex]\vec{x}\neq \vec{0}[/tex]

    2. The attempt at a solution

    Use the definition of cross product and tried to reduce it.
  2. jcsd
  3. Jan 21, 2010 #2


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    Science Advisor
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    Gold Member

    That is false as stated. Let x = <-2, 3, 1>, u = <1,2,3>, v = < 3,-1,2>. Then x cross u and x cross v are both <7,7,-7>. So your first step in solving the problem is to state it correctly.
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