图片中的两个问题无法放入 LaTeX

Question

$\left(x+a\right)^{2}+2ax+a^{2}$

Answer 1

作为起点：

\documentclass{article}

\usepackage{tikz}
\usetikzlibrary{tikzmark}

\begin{document}
\[
(x + \tikzmarknode{A}{a})^2 = x^2 + 2\tikzmarknode{B}{a}x + \tikzmarknode{C}{a}^2
%
\begin{tikzpicture}[overlay, remember picture,shorten <=1mm,
                    shorten <=1mm, shorten >=1mm]
\draw[->] (A.south) -- ++ (0,-0.5) -| node[pos=0.25, fill=white] {text} (B.south);
\draw[->] (A.south) -- ++ (0,-1.0) -| node[pos=0.25, fill=white] {text} (C.south);
\end{tikzpicture}
\vspace{3ex}    % space for image
\]
\end{document}

注意：为了获得正确的结果，您需要编译文档至少两次，通常三次。