How can I solve this differential equation? How can I find a solution of the following differential equation:
$$\frac{d^2y}{dx^2} =\exp(x^2+ x)$$
Thanks!

$\dfrac{d^2y}{dx^2}=e^{x^2+x}$
$\dfrac{dy}{dx}=\int e^{x^2+x}~dx$
$\dfrac{dy}{dx}=\int_k^xe^{x^2+x}~dx+C_1$
$y=\int\int_k^xe^{x^2+x}~dx~dx+\int C_1~dx$
$y=\int_k^x\int_k^xe^{x^2+x}~dx~dx+C_1x+C_2$
By http://mathworld.wolfram.com/RepeatedIntegral.html,
$y=\int_k^x(x-t)e^{t^2+t}~dt+C_1x+C_2$
