i know that answer is the following Please show me the step

Solution

I think you have to go through the link

http://www.stat.ufl.edu/STA4321/FALL06/Chapter%207%20Class.pdf

Page number 29-30 Example 7.8

I would prefer you should first describe the gamma distribution because we can characterize it in many ways. So as per the textbook (or the place where you are finding this problem) please first define the gamma distribution pdf.

You can revert me back if necessary.