\documentclass[12pt]{article} \usepackage{amssymb,amsmath,amscd,concmath,amsfonts} \usepackage{color} \pagestyle{empty} \begin{document} \begin{equation*} \frac{\partial\theta}{\partial t}= \frac{\partial^2\theta}{\partial x^2}, \end{equation*} \end{document}