Find (f −1)'(a). f(x) = 3x^3 + 2 sin x + 3 cos x, a = 3

Question

I don't know how to solve this question

Answer 1

f'(x) = 9x^2 + 2cosx
f(0) = 3
so (f^-1)'(3) = 1/f'(0) = 1/2

Answer 2

ah ty!