## LaTeX forum ⇒ TeXworks ⇒ How to recall the equation (1)?

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yaozhao
Posts: 27
Joined: Sat Oct 27, 2018 10:38 pm

### How to recall the equation (1)?

\begin{equation}MR=MC\end{equation}

Suppose this is the equation (2). In the article, I want to say, (2) can give us ......

How to recall (2)?

Maybe "recall" is not a good word here. Maybe retrieve?

Stefan Kottwitz
Posts: 9244
Joined: Mon Mar 10, 2008 9:44 pm
It's called referencing, and done by \label (to set a marker) and \ref or \eqref to reference that marker.
\documentclass{article} \usepackage{amsmath}\begin{document}\begin{equation}  \label{anotherone}  x = 2y\end{equation}\begin{equation}  \label{myformula}  MR=MC\end{equation}\eqref{myformula} can give us...\end{document}

Stefan

yaozhao
Posts: 27
Joined: Sat Oct 27, 2018 10:38 pm
Hi Stefan,

I used your codes. But when I refer, LaTeX gives me (??).

\documentclass[a4paper, 12pt]{article}  \usepackage{amsmath}\usepackage{amssymb}\usepackage[T1]{fontenc}	\usepackage{graphicx}\DeclareUnicodeCharacter{202F}{\,}In this way, we have the following equation in a perfectly competitive market:\begin{equation}\label{MR=P}MR=P\end{equation} Remember, \eqref{MR=P} only holds in perfectly competitive market because price is only fixed in this type of market.\\

Stefan Kottwitz