(xdy-ydx)/x^2=(1+(y/x)^2)xdx
d(y/x)=(1+(y/x)^2)xdx
d(y/x)/(1+(y/x)^2)=xdx
两边积分:arctan(y/x)=x^2/2+C
y/x=tan(x^2/2+C)
y=xtan(x^2/2+C)
(xdy-ydx)/x^2=(1+(y/x)^2)xdx
d(y/x)=(1+(y/x)^2)xdx
d(y/x)/(1+(y/x)^2)=xdx
两边积分:arctan(y/x)=x^2/2+C
y/x=tan(x^2/2+C)
y=xtan(x^2/2+C)