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Math Help - Need help solving for 'x' and 'y' in matrices...

  1. #1
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    Need help solving for 'x' and 'y' in matrices...

    Here is the equation:

    [3 2 -1]
    [-2 0 2]

    multiplied by

    [2 x]
    [-1 4]
    [3 y]

    equals

    [1 0]
    [2 4]


    instructions call to solve for x and y but i can seem to be able to find them, please help me. . .
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  2. #2
    Rhymes with Orange Chris L T521's Avatar
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    Quote Originally Posted by runner940 View Post
    Here is the equation:

    [3 2 -1]
    [-2 0 2]

    multiplied by

    [2 x]
    [-1 4]
    [3 y]

    equals

    [1 0]
    [2 4]


    instructions call to solve for x and y but i can seem to be able to find them, please help me. . .
    Once you multiply the matrices together, compare the values of the elements...

    \begin{bmatrix}3&2&-1\\-2&0&2\end{bmatrix}\begin{bmatrix}2&x\\-1&4&\\3&y\end{bmatrix}=\begin{bmatrix}1&0\\2&4\end  {bmatrix}

    Multiplying the two matrices together yields the equation \begin{bmatrix}1&3x+8-y\\2&-2x+2y\end{bmatrix}=\begin{bmatrix}1&0\\2&4\end{bma  trix}

    In comparing the elements, the only system that we need to solve is \left\{\begin{array}{rcrcr}3x&-&y&=&-8\\-x&+&y&=&2\end{array}\right.

    Do you think that you can find x and y now?

    --Chris
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  3. #3
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    when you multiply those matrices,you get 2*2 as dimensions of the answer which is
    1 3x-y+8 = 1 0
    2 -2x+2y = 2 4

    which means that 3x-y=-8 and -2x+2y=4
    -x+y=2 y=x+2
    3x-x-2=2

    2x=4

    x=2

    y=2+2=4



    S=(2,4)
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  4. #4
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    mr fantastic's Avatar
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    Quote Originally Posted by franckherve1 View Post
    when you multiply those matrices,you get 2*2 as dimensions of the answer which is
    1 3x-y+8 = 1 0
    2 -2x+2y = 2 4

    which means that 3x-y=-8 and -2x+2y=4
    -x+y=2 y=x+2
    3x-x-2=2

    2x=4

    x=2

    y=2+2=4



    S=(2,4)
    This solution is difficult to follow. The answer given is incorrect.
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