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Math Help - System of equations....

  1. #1
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    System of equations....

    Ok, i was just on a site for tutoring but it isn't making much sense to me!
    What steps do i follow through when doing this?

    y=3x+7
    y=x-9
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  2. #2
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by topaz192 View Post
    Ok, i was just on a site for tutoring but it isn't making much sense to me!
    What steps do i follow through when doing this?

    y=3x+7
    y=x-9
    There are several ways, the one I favor most is this:

    The two y values are equal, so let them be equal:
    x - 9 = 3x + 7

    2x = -16

    x = -8.

    Now use x = -8 in either one of the original equations:
    y = 3(-8) + 7 = -24 + 7 = -17

    So the solution is (x, y) = (-8, -17).

    -Dan
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