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How do I find f^-1(x) of the function f(x)= √x-9 ?

Find f^-1 and state its domain and range

√ x-9

Is it to basically find out the inverse of the function? How do I do this?

1 Answer

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  • 7 years ago
    Favorite Answer

    Substitute y for f(x) temporarily for convenience.

    y = √x - 9

    Swap x's and y's and solve for y.

    x = √y - 9

    x + 9 = √y

    (x + 9)^2 = y

    f^-1(x) = (x + 9)^2

    The domain of f(x) is [0, ∞) so the range of f^-1(x) = [0, ∞).

    The range of f(x) = [-9, ∞) so the range of f^-1(x) = [-9, ∞).

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