Find the coefficient a of the given term in the expansion of the binomial.

Question

Binomial: (x+4)12 Term: ax3 Find a:

Answer 1

n=12

the exponent of x decreases beginning with 12..

k=12-3=9

(12 choose 9) x^(12-9)(4^9)

(12 choose 9) x^3 4^9

(12*11*10/3*2)*4^9 x^3

3*2 cancels the 12;

2*11*10 = 220

220*4^9 x^3

57,671,680 x^3