\documentclass{standalone}
\usepackage{tikz}


\begin{document}
\begin{tikzpicture}
\draw[thin,->] (0,0)--(3.2,0);
\draw[thin,->] (0,0)--(0,3);
\draw[blue,thick] plot[smooth,domain=0:3]  function {2*(1-x**2/9)};
\draw[red,thick] plot[smooth,domain=0:3]  function {2.4*x*(1-x**2/9)};

\draw[red,thick] plot[smooth,domain=0:3]  function {2.4*x*(1-x**2/9)};
\draw[purple,thick] plot[smooth,domain=0:2]  function {2*(1-x**2/3)};


\node[blue] at (.5,2.2) {$c(\rho)$};
\node[red] at (2.8,2.2) {$c(\rho)\rho$};
\node[purple] at (2.3,-.5) {$v(\rho)$};


\node[below] at (3,0) {$\bar{\rho}$};
\draw[dashed] (1.73205080756888,2.77)--(1.73205080756888,0);
\node[below] at (1.73205080756888,.05) {${\rho^*}$};


\end{tikzpicture}
\end{document}