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Homework Help: Matrices trouble, finding k so matrix is rank 2

  1. Oct 10, 2005 #1
    Hello everyone, I have a problem...
    I am suppose to Find the value of k for which the matrix:

    A =
    -4 9 14
    2 7 16
    -7 -2 k

    has rank 2.
    k = ?

    I row reduced until i couldn't do it anymore and i got the following:
    -4 9 14
    0 23 46
    0 0 92k + 2116

    now i'm lost on how i'm suppose to find a value for k that will make this mantrix rank 2. ANy help would be great
     
  2. jcsd
  3. Oct 10, 2005 #2
    Just put 92k + 2116 = 0 since the rank of the matrix is determined by the number of non-zero rows when in row echelon form.
     
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