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Math Help - I need help on this ratio problem.

  1. #1
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    Question I need help on this ratio problem.

    Okay. Here is the problem.

    2(x^2+ y^2) = 5xy

    Please try to solve it.

    Thank you.
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  2. #2
    Super Member

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    Hello, necromancer745!

    The instructions are missing.
    We can't solve an equation with two variables in it.

    I'll assume that we want the ratio: y/x


    2(x + y) .= .5xy
    We have: .2x + 2y .= .5xy . . 2y - 5xy + 2x .= .0

    Divide by x: .2(y/x) - 5(y/x) + 2 .= .0


    Let u = y/x

    and we have: .2u - 5u + 2 .= .0

    . . which factors: .(u - 2)(2u - 1) .= .0

    . . and has roots: .u .= .2,


    Back-substitute and we have: .y/x = 2 .and .y/x =

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