How to make the table of solutions of a inequalities system?

my question is: how to make the table of solutions of a inequalities system and a table of sign of rational inequalities in LaTex?

Lot of similar question are discussed in many italian and english website and forum, but no one have THE answer. Moreover, all the talking are old, so now i'm gonna ask you if there is a solution for my problem. I need something like this

and

If no one have an answer, what program* can i use for produce images like these?

*I have the entire adobe and office packages, for example.

Really thanks and sorry for my english!

Try this code:

\documentclass[tikz,border=3.14mm]{standalone}

\begin{document}
\begin{tikzpicture}
\draw (-3,0)--(3,0);
\foreach \x in {-2,-1,2}{
\draw (\x,-1.5)--(\x,.1);
\node[above] at (\x,0.1) () {\small \x};}
\node[left] at (-2.5,-.5) {$f_1$};
\draw[dashed] (-2.5,-.5)--(-1,-.5) ;
\draw[fill] (-1,-.5) circle(2pt) (-1,-.5)--(3,-.5);
\node[left] at (-2.5,-1) {$f_2$};
\draw (-2.5,-1)--(-2,-1);
\draw[fill] (-2,-1) circle(2pt);
\draw[dashed](-2,-1)--(2,-1) ;
\draw[fill] (2,-1) circle(2pt);
\draw (2,-1)--(3,-1);
\node[left] at (-2.5,-1.5) {$f_1\cdot f_2$};
\draw[dashed] (-2.5,-1.5)--(-2,-1.5);
\draw[fill] (-2,-1.5) circle(2pt);
\draw(-2,-1.5)--(-1,-1.5) ;
\draw[fill] (-1,-1.5) circle(2pt);
\draw[dashed] (-1,-1.5)--(2,-1.5);
\draw[fill] (2,-1.5) circle(2pt);
\draw (2,-1.5)--(3,-1.5);
\end{tikzpicture}

\end{document}


Output:

FOR THE SECOND IMAGE replace the tikzpicture with this code:

\begin{tikzpicture}
\draw[-latex] (-6,0)--(2,0);
\foreach \x in {-5,-4,1}{
\draw (\x,-2)--(\x,.1);
\node[above] at (\x,0.1) () {\small \x};}
\node at (-5,-.05) () {*};
\draw (-6,-1.5)--(2,-1.5);
\node at (-4.5,-.5) () {+};
\node at (-2,-.5) () {-};
\node at (1.5,-.5) () {+};
\node at (-4.5,-1) () {+};
\node at (-2,-1) () {+};
\node at (1.5,-1) () {+};
\node at (-5.6,-2) {-};
\node at (-4.5,-2) () {+};
\node at (-2,-2) () {-};
\node at (1.5,-2) () {+};
\node at (-5,-1.55) () {*};
\end{tikzpicture}


You have:

• Thank you very much! This work very well Commented Mar 5, 2022 at 8:34
• @manuelbravi No points? No accept answer? Thanks. Commented Mar 5, 2022 at 8:49
• @manuelbravi You can now vote for accepted answer. Yhanks. Commented Mar 5, 2022 at 9:09
• @manuelbravi Now you forget to click the big left arrow up. Commented Mar 6, 2022 at 22:28