fof^-1

[Osbarot]

if we take f(x)=(x^2)+x
and we find the inverse function saw fof^-1 sould be equal to x right?

 

[Dr.Peterson]

if we take f(x)=(x^2)+x
and we find the inverse function so f o f^-1 should be equal to x right?

That's part of what it means to be an inverse, yes.

But the inverse of this function is not a function, unless you omitted a domain restriction. Please state the whole problem, and show whatever work you've done.