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Homework Help: Matrice problem Please help

  1. Jan 28, 2009 #1

    HKP

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    1. The problem statement, all variables and given/known data
    Find all values of k such that the following homogenous system has non-trivial solutinos:
    kx + 2y + 2z = 0
    x + 2y + 2z = 0
    4x + (k-1)y +2z = 0

    2. Relevant equations



    3. The attempt at a solution
    I put it in to matrix form ( k 2 2 0
    1 2 2 0
    4 (k-1) 2 0 )
    Then i subtracted row 2 from row 1 to get
    k 2 2 0
    (1-k) 0 0 0
    4 (k-1) 2 0

    Then i said if k=1 then there are infinite many solutions.

    I don't know where to go from that.
     
  2. jcsd
  3. Jan 31, 2009 #2
    No, that's not right at all! I think you even forgot to interchange row 2 with row 1 in order to introduce a leading 1 in a11.
     
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