# Two solutions to one statement

First question here;

Hello, a friend of mine made this a while back, but can't remember the latex code to make it. I need to make it myself and have no idea how this is done. I need to know how. Thank you very much!

PS: he said he used no programs or expansions, only the basic LaTeX.

For example:

\documentclass{article}
\usepackage{amsmath}

\begin{document}

$b=\begin{cases} y_1-ax_1\\ y_2-ax_2 \end{cases}$

If amsmath is forbidden:

$\left\{ \begin{array}{l} y_1-ax_1\\ y_2-ax_2 \end{array} \right.$

\end{document}


Please observe, that the curly brace should be larger than this one in your question.

I add my simple two MWE.

\documentclass{article}
\usepackage{mathtools}

\begin{document}
$b=\left\{\begin{matrix} y_1-ax_1& \\ y_2-ax_2& \end{matrix}\right.$
\end{document}


\documentclass{article}
\usepackage{amsmath}
\usepackage{cases}

\begin{document}

\begin{numcases}{b=}
y_1-ax_1 & \nonumber \\
y_2-ax_2 &   \nonumber
\end{numcases}

\end{document}