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9 votes
What is the inverse of f(x)= 3x-9

User Gank
by
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1 Answer

14 votes
14 votes

If
f^(-1)(x) is the inverse of
f(x), then


f\left(f^(-1)(x)\right) = x

Given


f(x) = 3x-9

composing with the inverse function gives


f\left(f^(-1)(x)\right) = 3f^(-1)(x) - 9 = x

Solve for the inverse:


3f^(-1)(x)-9 = x \\\\ 3f^(-1)(x) = x+9 \\\\ \boxed{f^(-1)(x) = \frac x3 + 3}

User InsaneCat
by
3.2k points