newzzq
幼苗
共回答了21个问题采纳率:90.5% 举报
dx/dt=2t/(1+t^2)
dy/dt=1-1/(1+t^2)=t^2/(1+t^2)
dy/dx=(dy/dt)/(dx/dt)=t^2/(2t)=t/2
d^2y/dx^2=d(dy/dx)/dx=d(t/2)/dx=d(t/2)/dt /(dx/dt)=(1/2)/[2t/(1+t^2)]=(1+t^2)/(4t)
y=(1+x²)arctanx
y'=((1+x²)arctanx )'
=(1+x²)'arctanx+(1+x²)(arctanx)'
=2xarctanx+(1+x²)(1/(1+x²))
=2xarctanx+1
【梦华幻斗】团队为您答题.
请点击下面的【选为满意回答】按钮,同时可以【赞同】一下,
1年前
3