Question

Without expanding, find the coefficient of x^6y^3 in the expansion of (x+2y)^9

Answer 1

Answer:

9C3  = 84 i dont know how to write the symbols. sorry

Step-by-step explanation:

      for x⁶ y³    in   (x+2y)⁹

we know the general form tₙ₊₁=⁹cₙx⁹⁻ⁿ(2y)ⁿ

now putting, their values according to our question

x⁹⁻ⁿ=x⁶

9-n=6

n=3

same for y

we get the vale on n = 3 now put it in ⁿcₓ form we get ⁹c₃=84