Question

高数，求三阶导数

高数，求三阶导数请问，话波浪线的部分是如何计算的，求详细步骤，谢谢。

Answer 1

复合函数求导，对中间变量求导，中间变量再对变量求导

Answer 2

d^2y/dx^2 = 1/f''(t)
d^3y/dx^3 = d(d^2y/dx^2)/dx = [d(d^2y/dx^2)/dt](dt/dx)
= {-f'''(t)/[f''(t)]^2}/(dx/dt) = {-f'''(t)/[f''(t)]^2}/f''(t) = -f'''(t)/[f''(t)]^3