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Homework Help: Λa+µb+vc =0 constants not all zero c.(axb)=0

  1. May 13, 2009 #1
    1. The problem statement, all variables and given/known data

    past paper qu...

    λa + µb + vc = 0
    for some λ, µ, v not all zero show c.(axb)=0

    consider cases v not equal to 0 and v = 0

    3. The attempt at a solution

    not sure how to start so if someone could just point me in the right direction or offer another hint it may help me get started in the mean time i'll keep looking at it


    ok i think i made a bit of progress:-

    when v not= 0
    λa.(axb) + µb.(axb) + vc.(axb) = 0.(axb)

    so vc.(axb) = 0
    => c.(axb) = 0
    Last edited: May 13, 2009
  2. jcsd
  3. May 13, 2009 #2


    User Avatar
    Science Advisor
    Homework Helper

    Use properties of the dot and cross product. axb is perpendicular to both a and b, right?
    So a.(axb)=b.(axb)=0. And if a and b are parallel, then axb=0.
  4. May 13, 2009 #3
    ok this along with the progress i made earlier has helped me do the qu

    thanks alot :biggrin:
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