1. The problem statement, all variables and given/known data Assume the function f(x)=x^3+x has an inverse in R. Determine d/dx(f^-1(x)) at x=2. 2. Relevant equations (f^-1(x))'=1/f'(f^-1(x)) 3. The attempt at a solution y'=3x^2+1 (f^-1(x))'=1/(3y^2+1) now i substitute f^-1(2), y=10, into the equation but do not get the correct answer. I suspect that the mistake i am making is becuase i do not fully understand the question. Any help is greatly appreciated.