Question

Need help! which of the fallowing statements regarding (x+y)^n is correct? check all that apply.

A. the coefficients of x^a y^b and x^b y^a are equal.
B. For any term x^a y^b in the expansion, a+b=n.
C. for any term x^a y^b in the expansion, a-b=n.
D. The coeffients of x^n and y^n both equal 1.

I know B for sure. C is wrong I know that too, Im just not sure about A and D.

Answer 1

D is saying the coefficient of the 1st term is 1

here is a simple example of expanding a cubic

e.g. \[(x + y)^3 = x^3y^0 + 3 x^2y^1 + 3x^1y^2 + x^0y^3\]

this may help with A and D

Answer 2

thanks!