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Math Help - inverse function help..

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    Post inverse function help..

    Let f(x)=-x^{2}-12x+61 , x<-6. Find a formula for the inverse function.
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    Quote Originally Posted by omibayne View Post
    Let f(x)=-x^{2}-12x+61 , x<-6. Find a formula for the inverse function.
    1. Calculate domain and range of f:

    D_f=(-\infty, -6) and R_f=(-\infty, 97)

    2. Therefore the domain and range of the inverse function u is:

    D_u=(-\infty, 97) and R_u=(-\infty, -6)

    3. Let f : y = -x^2-12x+61 then
    <br />
u : x = -y^2-12y+61

    4. Solve this equation for y:

    y = -6\pm\sqrt{97-x} . And since y must be smaller than -6 the equation of the inverse function is:

    u(x) = -6-\sqrt{97-x}
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