- #26

- 169

- 0

so..

[tex]\int_{0}^{\infty} r e^{-\left(\frac{2}{a}+\gamma\right)r}dr = \left(\left(-\frac{r}{\alpha}-\frac{1}{\alpha^{2}}\right)e^{-\left(\frac{2}{a}+\gamma\right)r}\right)\right|^{\infty}_{0}[/tex]

??

And then inputting the limits:

[tex]\implies = \left(0-\frac{1}{\alpha^{2}}\right)[/tex]

??

Therefore:

[tex]\implies = \left(-\frac{4 \pi }{\alpha^{2}}\right)[/tex]

.. better?