%%
%% An UIT Edition example
%%
%% Example 10-03-1 on page 202.
%%
%% 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
\usepackage{amsmath}
\StopShownPreambleCommands
\begin{document}
\[
\begin{array}{rcll}
y & = & x^{2}+bx+c\\
& = & x^{2}+2\times\dfrac{b}{2}x+c\\
& = & \underbrace{x^{2}+2\times\dfrac{b}{2}x+\left(\frac{b}{2}\right)^{2}}-
{\left(\dfrac{b}{2}\right)^{2}+c}\\
& & \qquad\left(x+{\dfrac{b}{2}}\right)^{2}\\
& = & \left(x+\dfrac{b}{2}\right)^{2}-\left(\dfrac{b}{2}\right)^{2}+c
& \left|+\left({\dfrac{b}{2}}\right)^{2}-c\right.\\
y+\left(\dfrac{b}{2}\right)^{2}-c & = & \left(x+
\dfrac{b}{2}\right)^{2} & \left|\strut(\textrm{vertex form})\right.\\
y-y_{S} & = & (x-x_{S})^{2}\\
S(x_{S};y_{S}) & \,\textrm{or}\,
& S\left(-\dfrac{b}{2};\,\left(\dfrac{b}{2}\right)^{2}-c\right)
\end{array}
\]
\end{document}
