# How can I place 3 columns of equation systems?

I need to create the next set of equations in latex, at the moment the only thing I know is to create them independently but I need to place them as you can see in the attached image, thank you very much.

And I also need to label the equation.

$Roberts=\begin{cases} G_x = \begin{pmatrix} 1 & 0\\ 0 & -1 \end{pmatrix}\\ G_y = \begin{pmatrix} 0 & 1\\ -1 & 1 \end{pmatrix}\\ \end{cases}$

$Prewitt=\begin{cases} G_x = \begin{pmatrix} 1 & 0 & -1\\ 1 & 0 & -1\\ 1 & 0 & -1 \end{pmatrix}\\ G_y = \begin{pmatrix} 1 & 1 & 1\\ 0 & 0 & 0\\ -1 & -1 & -1 \end{pmatrix}\\ \end{cases}$

$Sobel=\begin{cases} G_x = \begin{pmatrix} -1 & 0 & -1\\ -2 & 0 & 2\\ -1 & 0 & 1 \end{pmatrix}\\ G_y = \begin{pmatrix} 1 & 2 & 1\\ 0 & 0 & 0\\ -1 & -2 & -1 \end{pmatrix}\\ \end{cases}$ ## 1 Answer (red lines show text borders)

You need to write your cases in one equation. Note: this equation is quite long and may happen that will spill out of border in your document ...

\documentclass{article}
%--------------- show page layout. don't use in a real document!
\usepackage{showframe}
\renewcommand\ShowFrameLinethickness{0.15pt}
\renewcommand*\ShowFrameColor{\color{red}}
%
\usepackage{lipsum}                             % for dummy text
%---------------------------------------------------------------%

\usepackage[margin=25mm]{geometry}
\usepackage{amsmath}

\begin{document}
\lipsum
\begin{equation}                  % changed
\setlength\arraycolsep{3pt}% added
\text{Roberts}
=\begin{cases}
G_x = \begin{pmatrix}
1 & 0\\
0 & -1
\end{pmatrix}\$3ex] G_y = \begin{pmatrix} 0 & 1\\ -1 & 1 \end{pmatrix} \end{cases} \text{Prewitt} =\begin{cases} G_x = \begin{pmatrix} 1 & 0 & -1\\ 1 & 0 & -1\\ 1 & 0 & -1 \end{pmatrix}\\[4ex] G_y = \begin{pmatrix} 1 & 1 & 1\\ 0 & 0 & 0\\ -1 & -1 & -1 \end{pmatrix} \end{cases} \text{Sobel} =\begin{cases} G_x = \begin{pmatrix} -1 & 0 & -1\\ -2 & 0 & 2\\ -1 & 0 & 1 \end{pmatrix}\\[4ex] G_y = \begin{pmatrix} 1 & 2 & 1\\ 0 & 0 & 0\\ -1 & -2 & -1 \end{pmatrix} \end{cases} \end{equation} \lipsum \end{document}  Edit: Now equation has number. Also are changed size of \arraycolsep that equation can fit in determined page layout in above MWE, • And how can I label it and put the typical number of the equations? Thank you – Alejandro Fernández Suárez Oct 9 '20 at 17:45 • @AlejandroFernándezSuárez,as any numbered equation; instead \[ and $ use \begin{equation} and \end{equation respectively. See edited answer. – Zarko Oct 9 '20 at 17:59
• Oh yes! That's perfect! Thank you so much for all – Alejandro Fernández Suárez Oct 10 '20 at 12:31