\documentclass[12pt,a4paper]{article}
\usepackage[francais]{babel}
\usepackage{mafr}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{lmodern}
\usepackage[dvipsnames]{xcolor}
\usepackage{pstricks}
\usepackage{pstricks-add}
\begin{document}
\begin{pspicture*}(-3.5,-3.5)(3.5,3.5)%
\psgrid[gridcolor=lightgray,griddots=20,%
        subgriddiv=1,gridlabels=0pt,gridwidth=.4pt]%
       (0,0)(-3.5,-3.5)(3.5,3.5)%
\begin{footnotesize}%
\psaxes[arrows=->](0,0)(-3.5,-3.5)(3.5,3.5)%
\end{footnotesize}%
\psplot{-3.5}{3.5}{x 2 exp x add 2 sub}%
\end{pspicture*}
\end{document}
