把y当作函数先对x求导,再把x当系数对y求导.y+xy'+y'(e^y)=1.(1),解出y'=?.(2)
将（1）再对x求导.y'+y'+xy''+y''(e^y)+y'[(y')(e^y)]=0.(3)
将(2)结果带入(3).解出y