%% 
%%  Example 01-21-1 
%%  Copyright (C) 2017 Herbert Voss
%% 
%% ==== 
% Show page(s) 1
%% 
%% 
\documentclass[]{screxa}
\pagestyle{empty}
\setlength\textwidth{134.31393pt}

%StartShownPreambleCommands
\usepackage{xcolor}
%StopShownPreambleCommands
\begin{document}
\begin{equation}
\textcolor{blue}{f(x)} = \int\limits_1^{\infty}
   \textcolor{red}{\frac{1}{x^2}}\,\mathrm{d}x=1
\end{equation}
\end{document}
