%%
%% The LaTeX Companion, 2ed (second printing August 2004)
%%
%% Example 8-2-7 on page 473.
%%
%% Copyright (C) 2004 Frank Mittelbach, Michel Goossens,
%%    Johannes Braams, David Carlisle, and Chris Rowley
%%
%% 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.
%%

\documentclass{ttctexamargin}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{207.0pt}

\StartShownPreambleCommands
\usepackage{amsmath}
\StopShownPreambleCommands
\begin{document}
\begin{equation}
 \begin{split}
 (a + b)^4
   &= (a + b)^2 (a + b)^2      \\
   &= (a^2 + 2ab + b^2)
      (a^2 + 2ab + b^2)        \\
   &= a^4 + 4a^3b + 6a^2b^2 + 4ab^3 + b^4
 \end{split}
\end{equation}
\end{document}