对x求导(e^y)', 此处y是x的函数所以=e^y*y'(xy)'=x'*y+x*y'=y+x*y'e'=0所以e^y*y'+y+x*y'=0(e^y+x)*y'+y=0y'=-y/(e^y+x)
e^y+xy-e=0d(e^y) + d(xy) - d(e) = 0e^y dy + xdy + ydx = 0(e^y + x)dy = -ydxdy/dx = -y/(e^y + x)
把y看成x的函数,两边求导,的e^y.y'+y+xy'=0可得y'=-y/e^y+x