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Please help, need to find f^-1 (x)

Please help, need to find f^-1 (x)-example-1
User Vintastic
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1 Answer

14 votes
14 votes

The inverse function
f^(-1)(x) is such that


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

Plugging
f^(-1)(x) into
f(x) gives us


f\left(f^(-1)(x)\right) = (3f^(-1)(x) + 3)/(5f^(-1)(x) + 6) = x

Solve for
f^(-1)(x) :


(3f^(-1)(x) + 3)/(5f^(-1)(x) + 6) = x \\\\ 3f^(-1)(x)+3=x\left(5f^(-1)(x)+6\right) \\\\ 3f^(-1)(x) + 3 = 5x f^(-1)(x)+6x \\\\ 5xf^(-1)(x)-3f^(-1)(x) = 3 - 6x \\\\ (5x-3)f^(-1)(x)=3-6x \\\\ \boxed{f^(-1)(x)=(3-6x)/(5x-3)}

User Octavian
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