Binomial Theorem/General Binomial Theorem/Proof 2

Proof
From Sum over k of r-kt choose k by r over r-kt by z^k:


 * $\displaystyle \sum_n \dbinom {\alpha - n t} k \dfrac \alpha {\alpha - n t} z^n = x^\alpha$

where:
 * $z = x^{t + 1} - x^t$
 * $x = 1$ for $z = 0$.

Setting $t = 0$: