\documentclass[12pt]{article}
\thispagestyle{empty}
\usepackage{hyperref}
\usepackage{amsmath}
\begin{document}
\huge{
$a_{\beta} \langle \psi_{\alpha} | \psi_{\beta} \rangle = a_{\alpha} \langle \psi_{\alpha} | \psi_{\beta} \rangle $
}
\end{document}
