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Thread: Find A-2B

  1. #1
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    Question Find A-2B

    A= 5 1 B= -1 3
    3 2 4 1 Find A-2B
    My answer is -1 3
    4 1 I don't think this is right after using excel, thanks for checking.
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  2. #2
    Grand Panjandrum
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    Quote Originally Posted by kwtolley
    A= 5 1 B= -1 3
    3 2 4 1 Find A-2B
    My answer is -1 3
    4 1 I don't think this is right after using excel, thanks for checking.
    $\displaystyle
    A=
    \left[ \begin{array}{cc}
    {5}& {1}\\
    {3}& {2}
    \end{array} \right],\ B=
    \left[ \begin{array}{cc}
    {-1}& {3}\\
    {4}& {1}
    \end{array} \right].
    $

    so:

    $\displaystyle
    A-2B=
    \left[ \begin{array}{cc}
    {5}& {1}\\
    {3}& {2}
    \end{array} \right]-
    2 \times
    \left[ \begin{array}{cc}
    {-1}& {3}\\
    {4}& {1}
    \end{array} \right]
    $


    $\displaystyle
    =
    \left[ \begin{array}{cc}
    {5}& {1}\\
    {3}& {2}
    \end{array} \right]-
    \left[ \begin{array}{cc}
    {-2}& {6}\\
    {8}& {2}
    \end{array} \right]=
    \left[ \begin{array}{cc}
    {7}& {-5}\\
    {-5}& {0}
    \end{array} \right]
    $
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  3. #3
    Member
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    Jun 2006
    Posts
    165

    Smile thanks

    I thought mt answer was wrong. thanks again
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