Code: Select all
\documentclass{beamer}
\usepackage{fourier}
\begin{document}
\begin{frame}
$\tilde x$
\end{frame}
\end{document}
Code: Select all
\documentclass{beamer}
\usepackage{fourier}
\usefonttheme{serif} % here, there are other solutions
\begin{document}
\begin{frame}
$\tilde x$
\end{frame}
\end{document}