How to write equation where all equation are in only opening curly bracket and there is no closing curly bracket and with equation number

Question

How to write equation where all equation are in only opening curly bracket and there is no closing curly bracket and with equation number

Answer 1

I suggest you embed a

\left\{ \begin{aligned} ... \end{aligned} \right.

construct in an ordinary equation environment.

\documentclass{article} % or some other suitable document class
\usepackage{amsmath} % for 'aligned' environment
\begin{document}

\begin{equation}
\left\{
\begin{aligned}
a &= b+c \\
d &= e+f \\
g &= h+i \\
j &= k+l
\end{aligned}
\right.
\end{equation}

\end{document}