设函数y=tan的平方(1+X的平方),求y的微分Dy.

dy=2tan(1+X^2)dtan(1+X^2)=2tan(1+X^2)* 1/cos^2(1+X^2)d(1+X^2) =

2tan(1+X^2)* 1/cos^2(1+X^2)*2xdX =4x*sin(1+X^2)/cos^3(1+X^2) *dx