Find the coeficcient of the x4y3 term in the expansion of (2x+y)7

By the binomial theorem,

where

is the binomial coefficient.

We get the x⁴y³ terms with k = 3, for which the coefficient would be

step-by-step explanation:

x^2 -12x + 36 + y^2 = 36

x^2 + y^2 = 12x

r^2 = 12rcos(theta)

r = 12 cos(theta)