begin equation command

Hello,
Several errors appear when inserting begin equation command in beamer. Here
I copy what I have written:
\documentclass[xcolor=dvipsnames,11pt]{beamer}
\usepackage{xcolor}
\usecolortheme[named=LimeGreen]{structure}
\usetheme{Luebeck}

\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{graphicx}

\begin{document}
\maketitle

\begin{frame}
 \vspace{5pt}
\centering
%\begin{equation}
$V(r\cdot {m}_{1}, r\cdot{m}_{2})= r\cdot V(m_{1}, m_{2})$
%\end{equation} \\


\end{frame}
\end_{document}

Thank you!


-- 
Lei



   -
*La duda es uno de los nombres de la inteligencia. *
   -


* Only two things are infinite, the universe and human stupidity, and I'm
   not sure about the former. *
   -
*Quand la verité n'est pas libre, la liberté n'est pas vraie. *
   - *Da weiß man, was man hat.*
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