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Math Help - Functions

  1. #1
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    Post Functions

    What is the largest domain of the f(x)=x^2-x-12 which has an inverse function?
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  2. #2
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    Re: Functions

    I don't understand the question. That function cannot have an inverse since it is not a 1-1 function.
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  3. #3
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    Re: Functions

    Quote Originally Posted by aritra719 View Post
    What is the largest domain of the f(x)=x^2-x-12 which has an inverse function?
    The inverse relation to a vertical parabola is a horizontal parabola. So where is the vertex of the inverse relation? That will be the starting point for your domain.

    -Dan
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    Re: Functions

    Quote Originally Posted by grillage View Post
    I don't understand the question. That function cannot have an inverse since it is not a 1-1 function.
    No, but you can define new functions having that same "formula" but restricted domains that do have inverses. The crucial point is, as topsquark suggests, that x^2- x- 12= x^2- x+ 1/4- 49/4= (x- 1/2)^2- 49/4.
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