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Math Help - solve the system

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    solve the system

    x^2+y^2=16

    y+2x=-1
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  2. #2
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    Quote Originally Posted by uglygreencouch View Post
    x^2+y^2=16

    y+2x=-1
    Use substitution. I'd solve the bottom equation for y since it is linear in y, and thus simpler.

    y = -2x - 1

    Insert this into the top equation:
    x^2+(-2x - 1)^2=16

    x^2 + 4x^2 + 4x + 1 = 16

    Solve this for x (there will be two of them), then find your y values. (And check to make sure that both pairs fit your original equations, just to be on the safe side.)

    -Dan
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