\begin{exercice}[Des valeurs interdites!]
  \`A partir de chaque représentation graphique:
%\vspace{-.5em}  
  \begin{enumerate}
  \item déterminer la ou les valeur(s) pour la(les)quelle(s): 
  \begin{enumerate}
  \item la fonction n'est pas définie;
  \item la fonction est éventuellement nulle;
  \end{enumerate}
  \item établir le tableau de signes de cette fonction.
\begin{enumerate}
\item
  \begin{center}
  \begin{tikzpicture}[general, xscale=0.9, yscale=0.22]
   \draw[quadrillage, ystep=2, xstep=0.5] (-1,-14) grid (7,14);
    \axeX{-1}{7}{1}
   \axeY{-14}{14}{10}
   \origine
   \draw[epais, color=A1] plot[domain=-4:-0.094, smooth, samples=300, variable=\x] (\x+3,2+1.5/\x);
   \draw[epais, color=A1] plot[domain=0.115:4, smooth, samples=300, variable=\x] (\x+3,1+1.5/\x);
 \draw (6.5, 12.5) node[color=A1] {{\boldmath $\mathcal{C}_f$}};
 \end{tikzpicture}
 \end{center}



\item
  \begin{center}
  \begin{tikzpicture}[general, xscale=0.9, yscale=0.22]
   \draw[quadrillage, ystep=2, xstep=0.5] (-4,-14) grid (4,14);
   \axeX{-4}{4}{1}
   \axeY{-14}{14}{10}
   \origine
   \draw[epais, color=H1prime] plot[domain=-4:-1.61, smooth, samples=300, variable=\x] (\x,{(-0.5*(\x-2.5)/(-\x-1.5))-4});
   \draw[epais, color=H1prime] plot[domain=-1.379:4, smooth, samples=300, variable=\x] (\x,{-0.5*(\x-2.5)/(-\x-1.5)+2});
 \draw (3.5, 12.5) node[color=H1prime] {{\boldmath $\mathcal{C}_g$}};
 \end{tikzpicture}
 \end{center}
 \item 
 \begin{center}
  \begin{tikzpicture}[general, xscale=0.9, yscale=0.22]
   \draw[quadrillage, ystep=2, xstep=0.5] (-4,-14) grid (4,14);
  \axeX{-4}{4}{1}
   \axeY{-14}{14}{10}
   \origine
   \draw[epais, color=B1prime] plot[domain=-4:-2.045, smooth, samples=200, variable=\x] (\x,{((\x-1)*(\x+1)/(\x*\x-4))-2.65});
   \draw[epais, color=B1prime] plot[domain=-1.954:1.956, smooth, samples=200, variable=\x] (\x,{((\x-1)*(\x+1)/(\x*\x-4))+1.5});
   \draw[epais, color=B1prime] plot[domain=2.06:4, smooth, samples=200, variable=\x] (\x,{(\x-1)*(\x+1)/(\x*\x-4)+0.62});
 \draw (3.5, 12.5) node[color=C1] {{\boldmath $\mathcal{C}_h$}};
 \end{tikzpicture}
 \end{center}
 \end{enumerate}
   \end{enumerate}
\end{exercice}
