What does 'r' actually stand for in the binomial expansion?
no idea. Usually, it is written as
(a+b)^n =
n
∑ nCk a^(n-k) b^k
k=0
not sure what "r" you are referring to.
(a+b)^n =
n
∑ nCk a^(n-k) b^k
k=0
not sure what "r" you are referring to.