%% 
%%  An UIT Edition example
%% 
%%  Example 04-20-5 on page 70.
%% 
%%  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
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\documentclass[]{exaarticle}
\pagestyle{empty}
\setlength\textwidth{375.57637pt}
\AtBeginDocument{\setlength\parindent{0pt}}
\StartShownPreambleCommands
\newcommand*\dy{\,\mathrm{d}y}
\newcommand*\dx{\,\mathrm{d}x}\newcommand*\dyx{\,\frac{\mathrm{d}y}{\mathrm{d}x}}
\newcommand*\ds{\,\mathrm{d}s}\newcommand*\dt{\,\mathrm{d}t}
\newcommand*\dst{\,\frac{\mathrm{d}s}{\mathrm{d}t}}
\StopShownPreambleCommands
\begin{document}
\[ ay^\prime=a\dyx \quad c\times v = c\,\dst \quad
   a = \frac{\mathrm{d}^2t}{\dt^2} \quad \int\!\!\dy=\int\!\sin(x)\dx \]
\end{document}