let
z= e^(xy)
lnz = xy
(1/z) z' = xy' + y
z' = (xy' +y) e^(xy)
y =e^(xy) + x+1
y ' =(xy' +y) e^(xy) +1没懂...letz= e^(xy)lnz = xy(1/z)dz/dx = xdy/dx + ydx/dx(1/z)z' = xy' +yy =e^(xy) + x+1y ' =(xy' +y) e^(xy) +1