How do I edit this matrix system of equations?

Question

Is there a way to remove the right vertical line in the following matrix?

\documentclass{article}
 \usepackage{amsmath}
\begin{document}
   $    \begin{vmatrix} \alpha & -& \beta =180\\ \alpha & +&\beta =68
\end{vmatrix}$  
\end{document}

Answer 1

You maybe want to use systeme, rather than a matrix for that, which makes for even easier input:

\documentclass{article}
\usepackage{amsmath}
\usepackage{systeme}

\begin{document}

\[
\systeme[\alpha\beta]{
  \alpha-\beta=180,
  \alpha+\beta=68
}
\]
\[
\sysdelim|.
\systeme[\alpha\beta]{
  \alpha-\beta=180,
  \alpha+\beta=68
}
\]
\[
\syssubstitute{{a}{\alpha}{b}{\beta}}
\systeme[\alpha\beta]{
  3\alpha -  \beta = 180,
   \alpha + 2\beta = 68
}
\]

\end{document}

The traditional grouping is done with a brace, but you can also use a vertical bar as shown. If you want that all your systems have a vertical bar, type the \sysdelim|. command in the preamble.

Latin letters need not be declared as variables in the optional argument to \systeme.

Answer 2

It does work with matrix:

\documentclass{article}
\usepackage{amsmath}

\begin{document}

\[
\left| \begin{matrix}
\alpha & -& \beta =180\\ \alpha & +&\beta =68
\end{matrix} \right.
\]

\end{document}

Answer 3

I would do

\documentclass{article} 
\usepackage{amsmath} 
\begin{document} 
$ \left| \begin{array}{@{}*{4}{c@{\,}}l} 
\alpha & -& \beta &=&180\\ 
\alpha & +&\beta &=&68 
\end{array}\right.$ 
\end{document}

This is more effort, but avoids potential headaches like here, here and here.