Question

In this formula, what is r? I think it is the column of the pascal´s triangle I want, but I am not sure if the first column is column 1 or column 0

Answer 1

\[\left(\begin{matrix}n \\ r\end{matrix}\right)a ^{n-r}b ^{r}\]

Answer 2

n is the exponent...but r...i dont know

Answer 3

r is the position of the term in the row

Answer 4

but is the first position (always 1) counted? or it counts as term 1?

Answer 5

as term 0*

Answer 6

For example, if I want the middle term of (a+b)^12, I know I want the sixth term. r should be 5 or 6?

Answer 7

(a+b)^n, pick the rth term is what im thinking

Answer 8

(a+b)^3 = a^3 + 3a^2b + 3ab^2 + b^3

hmmm

Answer 9

3c0 3c1 3c2 3c3 are the coeefs that correspond to ncr

Answer 10

ok...then a^3 is term 0

Answer 11

so, r could be the term I want -1...thanks

Answer 12

sounds good :)