Find the integrating factor μ(x)\mu(x)μ(x) for y′+(2x1+x2)y=1(1+x2)2y' + (\frac{2x}{1+x^2})y = \frac{1}{(1+x^2)^2}y′+(1+x22x)y=(1+x2)21.
1+x21+x^21+x2
11+x2\frac{1}{1+x^2}1+x21
(1+x2)2(1+x^2)^2(1+x2)2
ln(1+x2)\ln(1+x^2)ln(1+x2)