# How to create a sign line for functions

I would like to create a tikz picture like the one included below. Can you help me with the code? Thanks.

For this purpose, the package tkz-tab can be used:

\documentclass[]{article}
\usepackage{tikz,tkz-tab}

\begin{document}
\begin{tikzpicture}
\tkzTabInit[espcl = 1.2]{$x$ / 1 , $f(x)$ / 1 , $g(x)$ / 1 , $h(x)$ / 1}{$-\infty$, $-2$, $-1$, $-3/4$, $2/3$, $3$, $+\infty$}
\tkzTabLine{, , , -, , , z, , +, , z, -,}
\tkzTabLine{, -, z, +, z, , -, , z, , +, , }
\tkzTabLine{, +, d, -, d, +, z, -, d, +, z, -}
\end{tikzpicture}
\end{document}


With the previous piece of code, one obtains