Hey All:

I was looking at a Beta function identity in a math physics book I have and

it said to show .

I done that OK. But....how does one prove

?.

I know the various gamma and beta identities, but got a little stuck on

where this comes from.

I know and so forth.

I tried various ways, but failed to get it to come together.

Where is the world do those factorials come from in that beta identity. I am missing something. Probably obvious. Always is.