SOLUTION: what is the coefficient of x^7 y in the expansion of (3x-4y)^8

Algebra ->  Exponential-and-logarithmic-functions -> SOLUTION: what is the coefficient of x^7 y in the expansion of (3x-4y)^8      Log On


   

Question 1146472: what is the coefficient of x^7 y in the expansion of (3x-4y)^8
Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


From the 8 factors of (3x-4y), you need to choose the "3x" term 7 times and the "-4y" term 1 time:

C%288%2C1%29%2A%283x%29%5E7%2A%28-4y%29%5E1

Use a calculator....