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%%  Ein Beispiel der DANTE-Edition
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%%  1. Auflage
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%%  Beispiel 09-07-17 auf Seite 447.
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%%  Copyright (C) 2011 Herbert Voss
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%%  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.
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%%  See http://www.latex-project.org/lppl.txt for details.
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\documentclass[]{exaarticle}
\pagestyle{empty}
\setlength\textwidth{352.81416pt}
\AtBeginDocument{\setlength\parindent{0pt}}
\setcounter{equation}{44}
\renewcommand\theequation{9.\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\cdot2a\Delta x+2^{2}\left(\Delta x\right)^{2}\right)\\
 +\left(a^{2}+2\cdot3a\Delta x+3^{2}\left(\Delta x\right)^{2}\right)\\
 + \ldots\\
\left.+\left(a^{2}+2\cdot(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}