Question

z=y/x,x=e^t,y=1-e^2t,求dz/dt

Answer 1

z'x=-y/x^2,z'y=1/x

x't=e^t,y't=-2e^(2t)

dz/dt=z'x*x't+z'y*y't=-y/x^2*e^t+1/x*-2e^(2t)

其他的自己代入吧