A Generalization of q-Binomial Theorem

Abstract

By using Liu's $q$-partial differential equations theory, we prove that if an analytic function in several variables satisfies a system of $q$-partial differential equations, if and only if it can be expanded in terms of homogeneous $(q,c)$-Al-Salam-Carlitz polynomials. As an application, we proved that for $c\neq0$ and $\max \{|cq|,|x|\}<1$, \begin{align*} \sum_{n=0}^{\infty} \frac{ (a;q)_n }{(cq;q)_n}x^n=(ax/c;q)_{\infty} \sum_{n=0}^{\infty} \frac{x^n}{(cq;q)_n}, \end{align*} which is a generalization of famous $q$-binomial theorem or so-called Cauchy theorem.