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Math Help - 3 simultaneous equations

  1. #1
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    Solve

    3x-y+2z=1
    2x+3y+3z=4
    x+y-4z=-9
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  2. #2
    Senior Member
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    You need to systematically eliminate one variable, say x, from the equations by subtracting a suitable multiple of one equation from all the others. Equation (3) begins with x so we'll use that.

    3x-y+2z=1 ... (1)
    2x+3y+3z=4 ... (2)
    x+y-4z=-9 ... (3)

    -4y + 14z = 28 ... (1)-3*(3) = (4)
    y + 11z = 22 ... (2)-2*(3) = (5)

    Now solve (4) and (5) for y and z and substitute the values for y and z into (3) to get x. Don't forget to check your answer!
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