Question

设y=f（u）二阶可导,求函数y=f（1/x）的二阶导数

Answer 1

y = f (1/x),

y' = f'(1/x)*(1/x)' = f'(1/x)*(-1/x^2),

y" = [f'(1/x)*(-1/x^2)]' = f"(1/x)*(-1/x^2)^2+f'(1/x)*(2/x^3).