The term containing x^4 in the expansion of (x + 2y)10

Answer 1

(x+2y)¹⁰

a = x

b = 2y

n = 10

General term is n C r a^n-rb^r where r = 0, 1, 2, .... n

^{So for the term with x^ 4 you need n-r = 4, so r = 6}

^{So the term will be 10 C 6 x^4 (2y) ^ 6 = 10 C 6 2^6 x^4 y^6 = 210 x 64 x^4 y^6 = 13440 x^4 y^6}