解答见图片
见图片
y=x+siny/2求导,得: y'=1+(cosy*y')/2,y'=2/(2-cosy)再求导,得:y''=(-siny*y'*y'+cosy*y'')/2再把y'==2/(2-cosy)代入,得:y''=4siny/(cosy-2)^3