How do I change the font size of something like this: I want to increase the font but it always seems to remain the same.
\documentclass[30pt]{article}
\DeclareMathSizes{20}{20}{20}{20}
\begin{document}
\[
x = \frac{1}{x + \frac{1}{x + \frac{1}{x}}}
\]
\end{document}