>>403
> 1）y=2x+3t^2
dy/dt=2dx/dt+6t

> 2)y=x^3t^4
dy/dt=3x^2t^4dx/dt+4x^3t^3

> 3)y=sin(ωt)
dy/dt=ωcos(ωt)

> 4)y=sin(3ωft-ω/4)
dy/dt=3ωfcos(3ωft-ω/4)