need help with inverse function problem.

1.find the inverse for:

$\displaystyle f(x)=x^4+2 x^3+ 3 x^2 + 2 x^2+1$?

and

this one is composite function problem

2.if $\displaystyle f(x y)=f(x+y)$ and given that $\displaystyle f(7)$=7, find the value of f(49)?

thanks for the reply...