%% 
%%  An UIT Edition example
%% 
%%  Example 09-16-5 on page 182.
%% 
%%  Copyright (C) 2010 Herbert Voss
%% 
%%  It may be distributed and/or modified under the conditions
%%  of the LaTeX Project Public License, either version 1.3
%%  of this license or (at your option) any later version.
%% 
%%  See http://www.latex-project.org/lppl.txt for details.
%% 
%% 
%% ==== 
% Show page(s) 1
%% 
\documentclass[]{exaarticle}
\pagestyle{empty}
\setlength\textwidth{375.57637pt}
\AtBeginDocument{\setlength\parindent{0pt}}
\setcounter{equation}{14}
\renewcommand\theequation{9.\arabic{equation}}
\StartShownPreambleCommands
\usepackage{gauss}
\StopShownPreambleCommands
\begin{document}
\begin{equation}
\begin{gmatrix}[b]
 1 &-2 & 1 & 2\\ 2 & 3 &-2 & 3\\  4 &-1 & 3 &-1\\ 3 & 2 &-4 & 5
\end{gmatrix} \times
\begin{gmatrix}[b]  x\\ y \\ z\\ t \end{gmatrix} =
\begin{gmatrix}[b]  8\\ 14\\ 7\\ 5 \end{gmatrix}
\end{equation}
\end{document}
