If $f(x)=x^3+3x^2+3x+1$, find $f(f^{-1}(2010))$.

Hint:  f( f^-1(a) )  =  a.

Wouldn't   f^-1(x)  have to be given a valid domain in order for it to be a function?

So    f( f^-1(x) ) =  f(x)  would only be strictly true for a given domain ?

But yes,  I guess that is what they are after.