两边对x求导,注意y是关于x的函数:
(e^y)'*y'+(xy)'=0
e^y*dx/dy+y+x*dy/dx=0
解得:dy/dx=-y/(e^y+x)
由原方程得:x=(e-e^y)/y
代入得:dy/dx=-y^2/[(y-1)e^y+e]
注意:最后尽量化为y的形式,不要有x出现.我大一学微积分时老师强调的.
求导后得e^ydy+ydx+xdy=0,再同时除以dx,得e^ydy/dx+y+xdy/dx=0,即dy/dx=-y/(e^y+x)
解:对方程两对求导,得
(e^y)*y'+y+xy'=0
整理得y'=-y/(x+e^y)
所以dy/dx=-y/(x+e^y)
e^y+xy-e=0
d(e^y) + d(xy) - d(e) = 0
e^y dy + xdy + ydx = 0
(e^y + x)dy = -ydx
dy/dx = -y/(e^y + x)