u=2x+3y,v=e^xydu=2dx+3dy,dy=(xdy+ydx)e^xy偏导数符号打不出来.用p代替吧,dz=(pz/pu)du+(pz/pv)dv=(pz/pu)(2dx+3dy)+(pz/pv)(xdy+ydx)e^xy=[2pz/pu+ye^xy pz/pv]dx + [3pz/pu+xe^xy pz/pv]dy