\documentclass{jarticle}

\begin{document}
% Enable preview-latex by C-c C-p C-d.  Answer with y to "Cache preamble?"
% question.  Then you will see that the image is placed on wrong position
% in the buffer.
preview-latex で \(a^{2}=b^{2}+c^{2}\) のような数式を日本語 LaTeX でも
preview したい。
\end{document}

%%% Local Variables:
%%% coding: euc-jp
%%% mode: japanese-latex
%%% TeX-master: t
%%% TeX-engine: ptex
%%% End: