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Math Help - sim. equ.

  1. #1
    Junior Member
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    sim. equ.

    x^2+y^2=20
    2y-x=0

    simultaneous equations- started but doing something wrong.
    please help
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  2. #2
    Math Engineering Student
    Krizalid's Avatar
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    Quote Originally Posted by lra11 View Post
    x^2+y^2=20
    2y-x=0
    From the second equation x=2y.

    Substitute that into the first equation, then solve for y, after that you'll get the values for x.

    --

    A related problem has been posted not long ago, let me find it and I'll edit my post. (Here is it. It's the same procedure.)
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  3. #3
    MHF Contributor red_dog's Avatar
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    From the second equation x=2y.
    Plug x in the first equation and you'll get
    x^2+4x^2=20\Leftrightarrow 5x^2=20\Leftrightarrow x^2=4\Leftrightarrow x=\pm 2.
    Then y=\pm 1.
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