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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
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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

    ...
    Hello,

    there are a lot of different ways to solve such a system. I'm going to show you the substitution method:

    1. Solve Q1 for y = -2x - 1

    2. Substitute this term instead of y into the Q2:

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

    3. Expand the bracket, collect like terms:

    x - 4x - 2 = 4

    -3x = 6
    x = -2

    4. Re-substitute the value of x into the first (modified) Q1:

    y = -2(-2) -1 = 3

    5. Therefore the solution is (-2, 3)

    EDIT: Please don't double post. It's only a waste of time
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