How do you use the binomial formula to find the coefficient of the z2x10 term in the expansion of (2x+z)12?

1 Answer
Feb 27, 2016

The coefficient of z2x10 is :

210C(12,2)=21012!10!2!=66×210

Explanation:

Binomial Theorem: (a+b)n=nk=0C(n,k)ankbk where the binomial coefficient C(n,k)=n!k!(nk)!

(2x+z)12=12k=0C(12,k)(2x)12kzk

Consider the k=2 term : C(12,2)(2x)10z2=C(12,2)210x10z2
So the coefficient of z2x10 is 210C(12,2)=21012!10!2!=66×210