I am somewhat confused.

Some text books refer to the following as the "General Form"

math]

(a+b)^n=\sum_{k=0}^{n}\binom{n}{k}a^{n-k}b^k

[/tex]

and others reverse the a^n and b^n-k

math]

(a+b)^n=\sum_{k=0}^{n}\binom{n}{k}a^{n-k}b^k

[/tex]

Are they both correct and if not when does one use the one or the other.

Any help would be great!!!!