![在数学环境中使用 tikz](https://linux22.com/image/422429/%E5%9C%A8%E6%95%B0%E5%AD%A6%E7%8E%AF%E5%A2%83%E4%B8%AD%E4%BD%BF%E7%94%A8%20tikz.png)
答案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}