\documentclass[12pt]{article}
\thispagestyle{empty}
\usepackage{hyperref}
\usepackage{amsmath}
\begin{document}
\huge{
$-a k^2\sin(k x) + -b k^2\cos(k x) = -a k^2 \sin(kx) + -b k^2 \cos(k x)$
}
\end{document}
