fig022a_rettafraz.pgf

% (c) 2012 Dimitrios Vrettos - d.vrettos@gmail.com
% (c) 2014 Daniele Masini - d.masini.it@gmail.com
\begin{tikzpicture}[font=\small]
\begin{scope}[thin,gray,xscale=2.5]
\foreach \x/\xtext in {%
-1,-.875,...,2
}
\draw[shift={(\x,0)}] (0pt,2pt) -- (0pt,-2pt);
\end{scope}
\begin{scope}[thick,xscale=2.5]
\draw[->] (-1.2,0) -- (2.2,0) node [above] () {$\insQ$};
\foreach \x/\xtext in {%
-1,0,1,2}
\draw[shift={(\x,0)}] (0pt,2pt) -- (0pt,-2pt) node[below] {$\xtext$};
\draw (0,0.5) -- node[above] {$u$} (1,0.5);
\draw (0,0.4) -- (0,0.6);
\draw (1,0.4) -- (1,0.6);
\end{scope}
\begin{scope}[scale=2.5]
\draw[fill] (1.5,0) circle (.5pt) node[below] {$\dfrac{3}{2}$};
\draw[fill] (-0.75,0) circle (.5pt) node[below] {$-\dfrac{3}{4}$};
\draw[fill] (0.625,0) circle (.5pt) node[below] {$\dfrac{5}{8}$};
\end{scope}

\end{tikzpicture}