[texhax] fbox in align environment

E. Krishnan ekmath at asianetindia.com
Tue Jun 16 02:18:25 CEST 2009

On Sun, 14 Jun 2009, Sebastian Canagaratna wrote:

> Say you have three equations in an align environment. You want to box
> only one of them, say the last one. How does one do this?

\usepackage{amsmath}

\begin{equation*}
\setlength{\arraycolsep}{0pt}
\renewcommand{\arraystretch}{1.25}
\begin{array}{r@{\;}c@{\;}r@{\;}}
x+y+2    & = & 1\\
2x+3y-4z & = & 2\\
\hline
\multicolumn{1}{|r@{\;}}{3x-2y+z}
& \multicolumn{1}{c@{\;}}{=}
& \multicolumn{1}{r@{\;}|}{3}\\
\hline
\end{array}
\end{equation*}

--
Krishnan