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

\begin{frame}

\begin{tikzpicture}[scale=1]
% Le repère
\draw[->, thick] (-3.5,0) -- (1,0); \draw[->, thick] (0,-1) -- (0,2);
\foreach \x in {-3,-2,-1,1} \draw (\x,1mm) -- (\x,-1mm) node[below] {$\x$};
\foreach \y in {-1,1}       \draw (1mm,\y) -- (-1mm,\y) node[left] {$\y$};

\draw plot[smooth] coordinates {(-3,0) (-2,1.5) (0,0) (1,1)};

\visible<2->{\draw[dashed] (-2,0)--(-2,1.5) node{$\bullet$};}
\visible<3->{\draw[dashed] (-2,1.5)--(0,1.5) node[right]{1,5};}
\end{tikzpicture}

\end{frame}