ltxtest.tex

\documentclass{article}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}
  \draw[domain = 0:2.2, smooth, variable=\x, blue, samples = 221]
        plot ({\x}, {sqrt(\x)})
        node[anchor = west] {$ y = \sqrt x $};
\end{tikzpicture}
\end{document}