（x^2+1)dy=(1-y^2)dx dy/(1-y)(1+y)=dx/(x^2+1) 1/2lnl(y-1)/(y+1)l=arctanx+c在帮我一个，我给再加五分，y′=y，y（0）=1.谢谢了dy/y=dxlny=x+c1y=ce^x y（0）=1得c=1y=e^x