%% 
%%  An UIT Edition example
%% 
%%  Example 06-03-5 on page 90.
%% 
%%  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}{33}
\renewcommand\theequation{6.\arabic{equation}}
\StartShownPreambleCommands
\usepackage{amsmath}
\StopShownPreambleCommands
\begin{document}
\begin{multline}
  A = \lim_{n\rightarrow\infty}\Delta x\left(a^{2}+\left(a^{2}+2a \Delta x
      +\left(\Delta x\right)^{2}\right)\right.\\
  +\left(a^{2}+2\times2a\Delta x+2^{2}\left(\Delta x\right)^{2}\right)\\
  +\left(a^{2}+2\times3a\Delta x+3^{2}\left(\Delta x\right)^{2}\right)\\
  + \ldots\\
  \left.+\left(a^{2}+2\times(n-2)a\Delta x+(n-2)^{2}
     \left(\Delta x\right)^{2}\right)\right)\\
  \left.+\left(a^{2}+2\times(n-1)a\Delta x+(n-1)^{2}
     \left(\Delta x\right)^{2}\right)\right)\\
  = \frac{1}{3}\left( b^{3}-a^{3}\right)
\end{multline}
\end{document}