Using the binomial theorem, find the coefficient of x^4*y^5 in (x-2y)^9.
The term containing x4y5 will be C(9, 5)x4(-2y)5 = (9!/(5!4!))x4(-2)5y5The coefficient of which will be 126-32=-4032
The term containing x4y5 will be C(9, 5)x4(-2y)5 = (9!/(5!4!))x4(-2)5y5The coefficient of which will be 126-32=-4032
