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Homework Help: Matrice word problem

  1. Jan 28, 2009 #1


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    1. The problem statement, all variables and given/known data
    Show that A + A(transpose) is symmetric for any square matrix A.

    2. Relevant equations
    A symmetric matrice is equal to A=A(transpose)

    3. The attempt at a solution

    I said A + A(transpose)
    = A(transpose) + A(transpose)
    = (A + A) (transpose)
    = A + A

    I don't know what else to do
  2. jcsd
  3. Jan 28, 2009 #2


    Staff: Mentor

    It looks like you're assuming that A is symmetric right at the start, which isn't information that you're given.

    Start with the definitions of AT and symmetric matrix.

    The definition you show for a symmetric matrix isn't right - I think you want this:
    A symmetric matrix A is such that A = AT. (A matrix can't be "equal" to an equation.)
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