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Math Help - Inverting fucntions

  1. #1
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    Inverting fucntions

    Having trouble inverting these functions, I get stuck when trying to solve for y,

    y=x+\sqrt{x}
    and
    y=\frac{1-\sqrt{x}}{1+\sqrt{x}}
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  2. #2
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    Hello !
    Quote Originally Posted by Robb View Post
    Having trouble inverting these functions, I get stuck when trying to solve for y,

    y=x+\sqrt{x}
    and
    y=\frac{1-\sqrt{x}}{1+\sqrt{x}}
    (\sqrt{x})^2+\sqrt{x}-y=0
    u^2+u-y=0

    Now solve this quadratic equation for u. The root has to be positive. So following the values of y, you'll have two expressions for u.
    Then substitute get back to x=u^2
    And you're done =)

    For the second one :
    y(1+\sqrt{x})=1-\sqrt{x}
    y+y\sqrt{x}=1-\sqrt{x}

    \sqrt{x}(y+1)=1-y

    \sqrt{x}=\frac{1-y}{1+y}

    ...
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