Ways of Describing Functions
\documentclass{standalone}
\usepackage{pgfplots} % Plotting library
\begin{document}
\begin{tikzpicture}
\begin{axis}[
xlabel = $x$,
ylabel = $f(x)$,
y = 1cm,
x = 1cm,
xmin = 0, xmax = 4, ymin = 0, ymax = 10,
axis lines = middle,
xlabel style = {anchor = west, xshift = 5pt},
ylabel style = {anchor = south, yshift = 5pt}
]
\pgfplotsinvokeforeach{0,...,3}{
\addplot[domain = 0:4, only marks, blue, very thick] coordinates {(#1, #1^2)};
}
\end{axis}
\end{tikzpicture}
\end{document}