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Homework Help: What's the pattern here?

  1. Mar 5, 2009 #1
    1. The problem statement, all variables and given/known data

    Alright so apparently there is some pattern in finding these determinants:

    for the 2x2, the determinant of
    |1 1|
    |x y| is y - x

    for 3x3, the determinant of

    |1 1 1 |
    |x y z |
    |x^2, y^2, z^2| is xy^2 - yx^2 - xz^2 +zx^2 + yz^2 - zy^2

    Apparently that can be factored (not sure how), and using the roots, there will be a pattern that you can observe for finding a determinant of a 4x4, 5x5, etc of the same form (1, x, x^2, x^3, etc.)

    How do you factor the 3x3 determinant, and what is the pattern? Does the determinant vanish at some point?
  2. jcsd
  3. Mar 5, 2009 #2


    User Avatar
    Science Advisor
    Homework Helper

    Start with the 3x3 case. The pattern is that the determinant vanishes in the cases x=y, x=z and y=x. Do you see why? Each of those tells you a factor of the determinant.
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