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Math Help - Simultaneous equations

  1. #1
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    Simultaneous equations

    My son has come home with some simultaneous equations, can anyone solve the following?

    Simultaneous Equations

    Q1.. 2x + y = -1

    Q2.. x + 2y = 4

    please show working out, will be easier for me to understand, and follow. if possible use a word file.

    Thanks
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  2. #2
    GAMMA Mathematics
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    Quote Originally Posted by duckegg911 View Post
    My son has come home with some simultaneous equations, can anyone solve the following?

    Simultaneous Equations

    Q1.. 2x + y = -1

    Q2.. x + 2y = 4

    please show working out, will be easier for me to understand, and follow. if possible use a word file.

    Thanks
    System of Equations can work via substitution or elimination. Elimination is the cleanest way:

    2x + y = -1
    x + 2y = 4

    Multiple the 2nd equation by -2 and then add the equations together.

    2x + y = -1
    -2(x + 2y = 4)
    ======================
    2x - 2x + y - 4y = -1 - 8

    -3y = -9

    y=3

    Plug the value of y back into either of the equations. The first one looks easiest.

    2x+3=-1

    2x=-4

    x=-2

    We have now solved for the system of equations by elimination.
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