MATH SOLVE

7 months ago

Q:
# what is the coefficient of the x^6y^3 term in the expansion of (x+2y)^9?

Accepted Solution

A:

use the binomial expansion formula for (a+b)^n

(sorry, cannot type it here, please google)

n!/[(n-k)!k!]a^(n-k)b^k

x^6y^3 is when k=3

in this case, n=9

so the coefficient when k=3 is: 9!/[(9-3)!3!]*(2)^3= [tex] \frac{9*8*7}{3*2*1} *2^3=672[/tex]

(sorry, cannot type it here, please google)

n!/[(n-k)!k!]a^(n-k)b^k

x^6y^3 is when k=3

in this case, n=9

so the coefficient when k=3 is: 9!/[(9-3)!3!]*(2)^3= [tex] \frac{9*8*7}{3*2*1} *2^3=672[/tex]