Hi guys

I recently ran into a problem after doing an integral, I'm left with $\displaystyle \frac{\beta^{\alpha}}{\Gamma(\alpha)}\frac{\Gamma( \alpha - k)}{\beta^{\alpha-k}}$

I know that I would be left with $\displaystyle $\beta^{k}$ on the numerator. But in the denominator. I'm not sure how the factorials would cancel.

Any help is appreciated