For any value of $n$, whether positive, negative, integer or non-integer, the value of the $n^{th}$ power of a binomial is given by: $ (a+b)^n=a^n+na^{n-1}b+\frac{n(n-1)}{2}a^{n-2}b^2+\dots+b^n $ or: $ (a+b)^n=\sum_{k=0}^n\frac{n!}{(n-k)!k!}a^{n-k}x^{k} $