I would like to plot these four equations :
$$y=\dfrac{3}{2x+1}, y=3x-2, x=2 y=0$$
and i don't know how to draw vertical line of equation x=2 and shade a region like the picture below

\documentclass{article}
\usepackage{pgfplots}
\usepackage{pst-plot}
\usepackage{pstricks}
\begin{document}
\begin{table}[h]
\centering
\begin{tikzpicture}
\begin{axis}[
extra y ticks = 2,
extra y tick labels = z,
extra y tick style = { grid = major },
axis lines=middle,
grid=major,
xmin=-1,
xmax=3,
ymin=-1,
ymax=3,
xlabel=$x$,
ylabel=$y$,
xtick={-1,-0.5,0,...,3},
ytick={-1,-0.5,0,...,3},
legend style={at={(axis cs:-.5,0,1)}, anchor=north west,width=90cm, draw=none,opacity=.9, inner sep=2pt,fill=gray!10}]
%\addlegendentry{$f(x)=2^{x}$}
%\addlegendentry{$f(x)={\left(\dfrac{1}{2}\right)}^x$}
smooth,
enlargelimits=false,
axis line style={latex-latex},
\addplot[thick, samples=100, domain=0:6,blue] {3/(2*x+1)}; %node[right] {$f(x)=2^{x}$};
\addplot[thick, samples=50, smooth,domain=0:6,olive] {3*x-2}; % node[right]{$f(x)={\dfrac{1}{2}}^x$};
\end{axis}
\end{tikzpicture}
\end{table}
\end{document}
which produces :



\addplot coordinates {(2, -1) (2, 3)};– MaxNoe Apr 26 '15 at 10:19+[mark=none]to the command:\addplot +[mark=none] coordinates {(2, -1) (2, 3)};– MaxNoe Apr 26 '15 at 10:33