\documentclass[12pt]{article}
\usepackage{amssymb,amsmath,amscd,concmath,amsfonts}
\pagestyle{empty}
\begin{document}
\begin{equation*}
  \dot q = g_1 (q) u_1 + \cdots + g_m (q) u_m.
\end{equation*}
\end{document}