\documentclass[12pt]{article}
\usepackage{amssymb,amsmath,amscd,concmath,amsfonts}
\usepackage{color}
\pagestyle{empty}
\begin{document}
\begin{equation*}
\frac{dz}{dt}=
  \left[\begin{matrix}
        -a_1 & -a_2 & -a_3 & \dots & -a_n \\
        1 & 0 & 0 & \dots & 0 \\
        0 & 1 & 0 & \dots & 0 \\
        \vdots & & \ddots & \ddots & \vdots \\
        0 & & & 1 & 0\\
  \end{matrix}\right] z+ \left[\begin{matrix}
    1 \\ 0 \\ 0 \\ \vdots \\ 0 
  \end{matrix}\right] u 
\end{equation*}
\end{document}