两边求导
xf(x)=2x+f'(x)
设f(x)=y
xy=2x+y'
y'=x(y-2)
dy/(y-2)=xdx
两边积分
lin(y-2)=1/2*x^2
y-2=e^(1/2*x^2)
y=e^(1/2*x^2)+2
即 f(x)=e^(1/2*x^2)+2
两边求导
xf(x)=2x+f'(x)
设f(x)=y
xy=2x+y'
y'=x(y-2)
dy/(y-2)=xdx
两边积分
lin(y-2)=1/2*x^2
y-2=e^(1/2*x^2)
y=e^(1/2*x^2)+2
即 f(x)=e^(1/2*x^2)+2