\documentclass[11pt, a4paper]{article} \usepackage{tkz-fct} \begin{document} \thispagestyle{empty} \begin{tikzpicture}[scale=0.85] \tkzInit[xmin=-3,xmax=5,ymin=-6,ymax=7] \tkzGrid[sub](-3,-6)(5,7) \tkzAxeXY \tkzFct[color=red, line width=1pt, domain=1.1:5]{-1/(x-1)} \tkzFct[color=red, line width=1pt, domain=-3:0.9]{-1/(x-1)} \tkzVLine[line width=1pt,color=blue]{1} \tkzSetUpPoint[size=3] \end{tikzpicture} \end{document}