What is the integrating factor of $2xy'+x^{2}e^{1-x^2}y=2$ I know how to start solving it, its dividing everything by $2x$, but I can't solve
$$\int \dfrac{x^2e^{1-x^2}}{2x}\,dx$$

$$\int \frac{x^2 e^{1-x^2}}{2x}dx=\int \frac{xe^{1-x^2}}{2}dx=-\frac{1}{2}\int\frac{-2xe^{1-x^2}}{2}dx$$ 
Let $u=1-x^2$ then $du=-2xdx$
$$=-\frac{1}{4}\int-2xe^{1-x^2}dx=-\frac{1}{4}\int e^udu =-\frac{1}{4}e^u$$
But $u=1-x^2$
$$\int \frac{x^2 e^{1-x^2}}{2x}dx=-\frac{1}{4}e^{1-x^2}$$
