Difficulty in solving a problem (COWA19E)

help
1

Can someone tell me the approach to solve Codewars Question(5) → COWA19E
Here is the link:

2

Tex2Img_1579428346%20(1)
Try solving it for some time.
I have written the reciprocal of the answer by mistake.

3

Thanks, it is just beta function,now it can be easily solved.