Find the positive integer n such that the expansion of (4x - 7y)^n contains a term of the form cx^2*y.
(4x - 7y)^n.
n cannot be 2, because you will get an xy term, and x^2 term, and a y^2 term with coefficients.
From binomial theorem logic, you can see that cx^a*y^b, where a = b + 1, and a + b = n, a = 2, so we have a + b = 3, and n = 3.
