原式变形：e^(-xy)+e^z=2z,首先e^(-xy)对x 求导,则y为常数,为e^(-xy)·(-y)；对y求导,则x为常数,为e^(-xy)·(-x)；其次e^z对x求导,同理得e^z·(dz/dx)；对y求导,同理得e^z·(dz/dy)；最后2z对x求导为2(dz/dx)；对y求...