Question

关于导数的一道题,希望有详解谢谢.

Answer 1

x= ln(1+t^2)

dx/dt = 2t/(1+t^2)

y= t-arctant

dy/dt = 1- 1/(1+t^2)

= t^2/(1+t^2)

dy/dx = dy/dt .(dx/dt)

= t/2

d^2y/dx^2 = (1/2) dt/dx

= (1/2)/[ 2t/(1+t^2)]

= (1+t^2)/(4t)