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# Latex numbering equations: leqno et fleqn, left,right

We’ll see how to number the Latex equations using the leqno and fleqn header functions.

## Number the equations on the right: fleqn

To number the equations on the right, we use the argument fleqn
in the class of the document: \documentclass. For example, in the case of an article in A4 format of size 10 points:

\documentclass[a4paper,10pt,fleqn]{article}
\begin{document}
\begin{eqnarray}
7x + 4y & =  & 0 \\
2x - 5y & =  & 0
\end{eqnarray}
\end{document}

Which gives: ## Number the equations on the left: leqno

To number the equations on the left, we use the argument leqno
dans la classe du document: \documentclass. For example, in the case of an article in A4 format of size 10 points:

\documentclass[a4paper,10pt,leqno]{article}
\begin{document}
\begin{eqnarray}
7x + 4y & =  & 0 \\
2x - 5y & =  & 0
\end{eqnarray}
\end{document}

Which gives: ## Delete the numbering of a line: \ noumber

To delete the number of a line we use the command \nonumber. This command must be placed at the end of the line whose number is to be deleted just before the line-break symbol (\) if it exists obviously!

\begin{eqnarray}
-\Delta  u & =  & f \\
u & =  & 0 \nonumber
\end{eqnarray} 