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Homework Help: Inverse Matrices Problem

  1. Jun 27, 2011 #1
    Hi :smile:

    I don't really know how to post a matrix here so I will try and make it as clear as possible.

    Matrix A: 4 -1
    2 3

    Matrix B: 6 4
    -5 -3

    Matrix C: 1 2
    3 4

    We are given that APB = C and we are asked for P

    What I did was I multiplied both sides by the inverse of (A*B), hence:

    P = (A*B)-1 * C

    I got a different answer than the book however, could anyone check?

    My answer:
    1.85 1.95
    2.85 2.95

    Book:

    1.6 1.8
    2.9 3.2

    Thanks,
    Peter G.
     
  2. jcsd
  3. Jun 27, 2011 #2

    SammyS

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    Staff Emeritus
    Science Advisor
    Homework Helper
    Gold Member

    Hi Peter,

    Matrix multiplication is not commutative!

    Multiply on the left by A-1 and on the right by B-1.
     
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