My code :
Code: Select all
\documentclass{article}
\usepackage{amsmath}
\usepackage{changepage}
\usepackage[utf8]{inputenc}
\begin{document}
\begin{eqnarray}
\frac{s}{b}\sum Zr + \sum\left[\beta\exp\Bigg\{\left(\frac{r-r}{\rho}\right)\Bigg\}+n \beta\exp\Bigg\{\left(\frac{2-r}{\rho}\right)\Bigg\}+\frac{n}{2}\beta\exp\Bigg\{\left(\frac{\r}{\rho}\right)\Bigg\}\right]
\end{eqnarray}
\end{document}