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Homework Help: Inverse of a weird looking matrix!

  1. Mar 11, 2009 #1
    1. The problem statement, all variables and given/known data

    If A =

    [ -4e^4t sin(9t) -4e^5t cos(9t) ]
    [ 4e^4t cos(9t) 4e^5t sin(9t) ]

    then what would A^-1 be?

    I think I am mainly confused with the cos's and sin's...and all that other junk...since I know how to get the inverse of a regular matrix!

    Thank you!

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Mar 11, 2009 #2
    Use the rule of thumb for 2x2-matrix divide the matrix through its determinant change positions of a and d and put a minus sign at b and c.
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