Tools able to generate tikz code are listed at http://tikz.de/tools
(sorry, the comments on that page are in german, but the links work in any language ...). Tikz, on its own, can be used to create beautiful graphs of equations, like so
\documentclass{article}
\usepackage{pgfplots}
\usepackage{tkz-euclide}
\usetkzobj{all}
\begin{document}
\pgfplotsset{every axis plot/.append style={very thick}}
\pgfplotsset{major grid style={dashed,gray}}
\pgfplotsset{minor grid style={white}}
\pgfplotsset{compat=1.12}
\begin{tikzpicture}[scale=.5]
\pgfplotsset{grid style={dashed,gray}}
\begin{axis}[
grid=both,
minor tick num=9,
axis x line=middle,
axis y line=middle,
every outer x axis line/.append style={|->},
every outer y axis line/.append style={|->},
width=16cm,
major tick length=1cm,
xlabel=$x$,
ylabel=$y$]
\addplot[blue,samples=500,domain=-10:260] {-2 * x*x + 500 * x};
\draw[red!50!black] (axis cs:125,31300) -- (axis cs:125,0);
\legend{$A(x)=-2x² + 500x$}
\end{axis}
\end{tikzpicture}
\end{document}
The right side of the equation A(x)=-2x² + 500x is argument to \addplot[...]{...}.