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Solving systems of equations by elimination

-4x+9y=9

X-3y=-6

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  1. 15 May, 18:53
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    Manipulate the equations until one of the variables match up

    I'm going to cancel the y-values.

    -4x+9y=9

    x-3y=-6

    the way to do that is to multiply all the numbers, on both sides of the equation, by 3.

    3 (x-3y) = 3 (-6)

    3x-9y=-18 Now that the y value matches up with the other one, add the 2 equations

    -4x+9y=9

    + 3x-9y=-18

    The resulting equation is - x=-9, so x=9.

    Plug this new x-value into one of the original equations to find the y-value.

    x-3y=-6

    (9) - 3y=-6

    -3y=-15, so y=5

    Check your work by plugging the 2 variables into both equations and the results should both be true.

    -4 (9) + 9 (5) = 9 - 36+45=9 9=9

    (9) - 3 (5) = - 6 9-15=-6 - 6=-6

    So y=5 and x=9
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