Can someone help with this, please? I'm realy struggling...
Thanks!
$\displaystyle
\int u^4 e^{\frac{-1}{2}u^2}\ du
$
$\displaystyle \int x^4 e^{-x^2/2} ~ dx = -\int x^3 \left( e^{-x^2/2} \right)' dx$
But, $\displaystyle \int x^3 \left( e^{-x^2/2} \right)' dx = x^3 e^{-x^2/2} - 3\int x^2 e^{-x^2/2} ~ dx$
But, $\displaystyle -\int x^2 e^{-x^2/2} dx = \int x \left( e^{-x^2/2} \right)' dx = xe^{-x^2/2} - \int e^{-x^2/2} ~ dx$
The last one has no primitive.