我是这样做的：dx/dt=2t
dy/dt=4t^3-6t^2
dy/dx=(dy/dt)/(dx/dt)=(4t^3-6t^2)/(2t)=2t^2-3t
d^2y/dx^2= (d/dt [dy/dx]) / [dx/dt]=(4t-3)/(2t)
把t=1代入，结果为1/2
dy/dt=4t^3-6t^2
dy/dx=(dy/dt)/(dx/dt)=(4t^3-6t^2)/(2t)=2t^2-3t
d^2y/dx^2= (d/dt [dy/dx]) / [dx/dt]=(4t-3)/(2t)
把t=1代入，结果为1/2
