# Math Help - Integration by parts...

1. ## Integration by parts...

2. Ok, I now get the first one but not the second...

3. Hint:
$\displaystyle \int_{-\infty}^{\infty} \frac{1}{\sqrt{2 \pi}} z^2e^{-z^2/2}$

Rewrite this as
$\displaystyle \int_{-\infty}^{\infty} \frac{1}{\sqrt{2 \pi}} z \cdot ze^{-z^2/2}$

Integration by parts:
$\displaystyle \int p dq = pq - \int q dp$

Use $\displaystyle p = z$ and $\displaystyle dq = ze^{-z^2/2}dz$

-Dan

Since you have the first, for the second my suggestion is to set p = z^3 and dq the same as in the first part.

4. Awesome thank you!