\documentclass[12pt]{article}
\usepackage{amssymb,amsmath,amscd,concmath,amsfonts}
\usepackage{color}
\pagestyle{empty}
\begin{document}
\begin{equation*}
  \begin{aligned}
    a(s) &= s^n + a_1 s^{n-1} + \cdots + a_{n-1} s + a_n\\
    b(s) &= b_0 s^{m} + b_1 s^{m-1} + \cdots + b_{m-1} s + b_m.
  \end{aligned}
\end{equation*}
\end{document}