Engineering Board Exam Reviewer · Functions: Domain, Composition, and Inverses · hard

If f(x)=x/x-1, find f(f(x)).

1. x
2. x2/(x-1)2
3. x/x-1
4. 1x

Answer

A. x

Solution

f(f(x))= x/x-1x/x-1-1= x/x-11/x-1=x. The function is its own inverse.

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