(1+x^2)dy+2xydx=0
(1+x^2)dy=-2xydx
1/y*dy=-2x/(1+x^2)*dx
两边同时积分得
∫1/y*dy=∫-2x/(1+x^2)*dx
ln|y|=-ln|1+x^2|+ln|c|
y=c/(1+x^2)
或
(1+x^2)y=c
(1+x^2)dy+2xydx=0
(1+x^2)dy=-2xydx
1/y*dy=-2x/(1+x^2)*dx
两边同时积分得
∫1/y*dy=∫-2x/(1+x^2)*dx
ln|y|=-ln|1+x^2|+ln|c|
y=c/(1+x^2)
或
(1+x^2)y=c