1. The problem statement, all variables and given/known data Let, f(x) = x^3 - 3x^2 - 1 , x => 2 . Find the value of df^-1/dx at the point x=-1=f(3) 2. Relevant equations The definition states; "If f has an interval I as domain and f'(x) exists and is never zero on I, then f'(c) is diff at every point in its domain. The value of (f^-1)' at a point b in the domain of f_1 is the reciprocal of the value of f1 at the point a = f^-1(b): Though I don't really understand what is going on in the equation. 3. The attempt at a solution The derivative is f' = 3x^2 - 6x , but I don't really get what and why I do what I have to do from here. Coulden't find a youtube video for these sort of problems.