在数学环境中使用 tikz

Question

在常规数学环境中，我该如何做下面（最左边）的事情？这是一个overlay选择吗？请告诉我。

Answer 1

就像这样——

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{tikzmark, positioning, fit, shapes.misc}
\usetikzlibrary{decorations.pathreplacing, calc}
\tikzset{brace/.style={decorate, decoration={brace}},
    brace mirrored/.style={decorate, decoration={brace,mirror}},
}
\begin{document}
    \tikzmark{a}126\tikzmark{b}0\tikzmark{c}0\tikzmark{d} ft
    \begin{tikzpicture}[remember picture, overlay]
        \draw[brace mirrored, thick](pic cs:a)--(pic cs:b) node[midway, below]{3?};
        \draw[brace mirrored, thick]($(pic cs:a)+(0pt, -12pt)$)--($(pic cs:c)+(0pt, -12pt)$) node[midway, below]{4?};   
        \draw[brace mirrored, thick]($(pic cs:a)+(0pt, -24pt)$)--($(pic cs:d)+(0pt, -24pt)$) node[midway, below]{5?};           
        \draw[dotted](pic cs:c)--($(pic cs:c)+(0pt, -12pt)$);
        \draw[dotted](pic cs:d)--($(pic cs:d)+(0pt, -24pt)$);
    \end{tikzpicture}

    
\end{document}