两边对x求导得:y+xy'+y'/y=0即:y'=-y^2/(xy+1)原方程代入指数函数得:e^(xy+lny)=e即:e^(xy) y=e于是:当x=0时,ey(0)=e, y(0)=1 y'(0)= -(y(0))^2/(0*y(0)+1) = -1
两边求导:y+xy'+y‘/y=0将x=0带入得到:y'=--y^2