答案1
使用matrix
库tikz
应该可以解决问题:
\documentclass[a4paper,11pt]{article}
\usepackage[margin=2cm]{geometry}
\usepackage{tikz}
\usetikzlibrary{backgrounds,decorations,decorations.pathreplacing,math,matrix,positioning,shadows,shapes.geometric}
\begin{document}
\begin{tikzpicture}
\matrix
{
\node {$(-5) \: \cdot$}; &[1mm] \node(eq1) {$2x + y = 5$}; &[5mm] \node(eq1a) {$-10x - 5y = -25$}; \\
\node {$(-2) \: \cdot$}; & \node(eq2) {$-5x + 3y = 2$}; & \node(eq2a) {$10x -6y = -4$};\\
};
\draw[thick,blue,decorate,decoration={brace,amplitude=2pt,mirror}] ([xshift=-2.5mm,yshift=2mm]eq1.west) -- ([yshift=-2mm]eq2.west);
\draw[thick,blue,decorate,decoration={brace,amplitude=2pt,mirror}] ([yshift=2mm]eq1a.west) -- node[left] {$\Rightarrow$} ([xshift=-2.3mm,yshift=-2mm]eq2a.west);
\draw[thick,blue] ([xshift=-15mm]eq2a.south) --+ (3,0);
\node(eq3) [below=of eq2a,yshift=8mm] {$-11y = -29$};
\node [right=of eq3,xshift=-7mm] {$\displaystyle \Rightarrow \quad y = \frac{-29}{-11}$};
\end{tikzpicture}
\end{document}