I need to find the coefficient of x^18 y^32 in (x+y)^50.

Question

I understand that we have to use the binomial theorem. I know how to
find the coefficient for example x^18 but here we have "x" as well as
"y" which I have no idea about.

Answer 1

general term(r+1)
= C(50,r)(x^(50-r) y^r

comparing this with ? x^18 y^32 we can see that r = 32
so we want C(50,32) which is 1.80535 x 10^13

Answer 2

How many monomials appear in the expansion of (x + y + z)^75?