求偏导数计算过程如下图所示:
yz+zx+xy=3两边求微分，得zdy+ydz+zdx+xdz+xdy+ydx=0dz=-(y+z)dx/(x+y)-(x+z)dy/(x+y)因此ðz/ðx=-(y+z)/(x+y) ðz/ðy=-(x+z)/(x+y)
