% Dans le préambule
% -----------------
\usepackage{tikz}
% -----------------

\begin{tikzpicture}[xscale=1,yscale=1.5]
  \tkzInit[xmin=-1.5,xmax=3,ymin=-1,ymax=1]
  \tkzAxeXY[orig=false,swap]
  \draw[domain = -1.5:3]
                plot (\x, {1/(1+(\x)^2)} );
  \draw (1,0.5) node[scale=1] {$\bullet$}
                node[above right] {$A$};
\end{tikzpicture}