what is the constant term in
I see you have graph paper.
You must be plotting something
In mathematics, you don't understand things. You just get used to them.
Of course that result can be rigorously obtained, but who cares?
Combinatorics is Algebra and Algebra is Combinatorics.
You need to calculate the coefficent where the z term is (z to the power zero).
That will be
So 9C3 x 2^6
You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei