# Math Help - Inverse function problem

1. ## Inverse function problem

Let f(x) = 5 + x2 + tan(πx/2), where -1 < x < 1.

Find f(f ^(-1)(7)).

I'm not sure finding the inverse function of this is possible, but think I can find out what x has to equal to get -7, which is the first part. How do I move onto the second part?

2. Originally Posted by the
Let f(x) = 5 + x2 + tan(πx/2), where -1 < x < 1.

Find f(f ^(-1)(7)).

I'm not sure finding the inverse function of this is possible, but think I can find out what x has to equal to get -7, which is the first part. How do I move onto the second part?
To me it looks like a trick question because

1. $f^{-1}(x)$ is the inverse function of f(x).

2. $f \left(f^{-1}(x)\right) = f^{-1}(f(x)) = x$

Can you take it from here?

3. Ah, yes! I fell for it, thanks!