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Eigen value Q. pls help

  1. Mar 12, 2008 #1
    For which value of does the matrix
    -4 k
    -3 -7

    have one real eigenvalue of multiplicity 2??

    I use det(µI-A)=0
    and end up with µ^2 - 3µ - 28 + 3k
    but i dont know where to go from here
    pls help
  2. jcsd
  3. Mar 12, 2008 #2
  4. Mar 12, 2008 #3
    haha thanks
  5. Mar 12, 2008 #4
    you sure you computed the determinant correctly?

    anyways after you correct it, hint: quadratic formula
  6. Mar 13, 2008 #5
    yea you did do it wrong... do it again and then think
  7. Mar 14, 2008 #6


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    Science Advisor

    In particular, after you have the correct equation, think about the discriminant of the equation.
  8. Mar 14, 2008 #7
    your help has been greatly appreciated
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