Answer
$y=Ce^{\frac{1}{2} x^2} -1$
Work Step by Step
Begin by separating the variable to each side in terms of x's and y's.
$\frac{dy}{dx}=x(1+y)$
$ \frac{1}{1+y} dy= x dx$
$ \int \frac{1}{1+y} dy = \int xdx$
Integrate
$ \ln{|1+y|} = \frac{1}{2}x^2 +C$
$1+y= e^{\frac{1}{2}x^2 +C}$
Let $e^C = C$
$ y= Ce^{\frac{1}{2}x^2} -1$