\documentclass[12pt]{article}
\usepackage{amssymb,amsmath,amscd,concmath,amsfonts}
\pagestyle{empty}
\begin{document}
\begin{equation*}
  M(\theta) \ddot\theta +
  C(\theta, \dot\theta) \dot\theta +
  N(\theta, \dot\theta)
  = \tau
\end{equation*}
\end{document}