2.y'+y/x=1dy/dx+y/x=1dy/dx=1-y/x;令y/x=u;y=ux,dy/dx=u+(du/dx)*xu+(du/dx)*x=1-udu/dx)*x=1-2udu/1-2u=dx/xln|x|=ln|1-2u|+Cx=1-y/x+Cy=x*x+(c+1)x另外的你自己改变符号就行.不知道你那个是平方么1.dy/(y*y)=2xdx...