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Math Help - Matrices Help.

  1. #1
    Newbie
    Joined
    Oct 2010
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    Matrices Help.

    This is the question i am trying to solve...
    http://img151.imageshack.us/img151/7596/mathprob.jpg
    U is a 3x3 matrix.

    However, when i put my answer in I get only part marks... 78% right.

    My attempt:
    I found that to get B, I had to use elementary row operations. Mine were:
    -2r1 + r2 --> r2
    and r1 + r3 --> r3

    after that I used an identity to find U, and i applied the same row operations.

    My matrix/U looked like this after:
    1 0 0
    -2 1 0
    1 0 1

    What am i doing wrong???




    UPDATE:
    I just figured it out...
    I just had to invert U to get my answer
    Last edited by mr fantastic; February 11th 2011 at 03:03 AM. Reason: Deleted begging for help in title.
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  2. #2
    A Plied Mathematician
    Joined
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    CT, USA
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    Glad you figured it out on your own, because the phraseology "I get only part marks" indicates that this problem is for a grade. It is forum policy not knowingly to help with such problems.
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