% 10-5-1.tex
\documentclass{article}
\DeclareMathSizes{12}{20}{14}{10} % 文稿中示例用
\begin{document}
{\large $x^{x^x}=B_{k_j}$}

{\Large $x^{x^x}=B_{k_j}$}

$x^{x^x}=B_{k_j}$

\section{\LaTeX\ and \LaTeXe}

\subsection{\LaTeX\ and \LaTeXe}

\end{document}