先求出x=0时y=e,(x=0带入ln(x+y)=e ^xy )ln(x+y)=e ^xy 两边对x求偏导(y'+1)/(x+y)=e^xy* (y+xy')令x=0有(y'|x=0 +1)/(0+e)=1*e有y'|x=0 =e^2-1
当x=0时,代入方程得lny=1,即y=e方程两边求导得(1+y')/(x+y)=e^xy×(y+xy')带入x=0,y=e得(1+y')/e=e即y'=-1+e^2