如何制作不等式组的解表？

Question

我的问题是：如何在 LaTex 中制作不等式系统的解表和有理不等式的符号表？

许多意大利语和英语网站和论坛都讨论过类似的问题，但没有人有答案。而且，所有的讨论都是陈词滥调，所以现在我要问你是否有办法解决我的问题。我需要这样的东西

和

如果没有人回答，我可以使用什么程序*来生成这样的图像？

*例如，我拥有整个 Adob​​e 和 Office 软件套件。

真的非常感谢并且抱歉我的英语不好！

Answer 1

试试这个代码：

\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}

输出：

对于第二张图片，用以下代码替换 tikzpicture：

\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 (-6,-.5) {N)\quad +}; 
        \node at (-4.5,-.5) () {+};
        \node at (-2,-.5) () {-};
        \node at (1.5,-.5) () {+};
        \node at (-6,-1) {D)\quad -}; 
        \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}

你有：