多列和数组中的间距

Question

以下展示了我最近在 LaTeX 中的工作：

我使用以下代码实现了这个功能：

\documentclass[12pt,lettersize]{article}
\usepackage[top=1.25in, bottom=1.05in, left=0.5in, right=0.5in]{geometry}
\usepackage{multicol}
\usepackage{amsmath,amssymb,amsthm}

\begin{document}

\begin{enumerate}

\item
Solve each system of equations algebraically.
    \begin{multicols}{2}
    \begin{enumerate} \itemsep=12pt
        \item $\left\{ \begin{array} {rcl} 2x + 3y & = & 3 \\ 12x - 15y & = & -4 \end{array} \right.$
        \item $\left\{ \begin{array} {rcl} y & = & 6-x \\ x & = & \dfrac{9}{2} + y \end{array} \right.$
        \item $\left\{ \begin{array} {rcl} x & = & 2y-8 \\ 2x-y & = & 7 \end{array} \right.$
        \item $\left\{ \begin{array} {rcl} \dfrac{3}{5}x - \dfrac{1}{6}y & = & 1 \\ \dfrac{1}{5}x + \dfrac{5}{6}y & = & 11 \end{array} \right.$
    \end{enumerate}
    \end{multicols}

\end{enumerate}
\end{document}

但是，项目 (d) 中的分数间距看起来很别扭。此外，(b) 与 (d) 不对齐。有什么解决方法吗？谢谢。

Answer 1

尝试在项目 d 的数组中的 \\ 后添加额外的 \\ 或 [9pt]：

\documentclass[12pt,lettersize]{article}
\usepackage[top=1.25in, bottom=1.05in, left=0.5in, right=0.5in]{geometry}
\usepackage{multicol}
\usepackage{amsmath,amssymb,amsthm}

\begin{document}

\begin{enumerate}

\item
Solve each system of equations algebraically.
 \begin{multicols}{2}
\begin{enumerate} \itemsep=12pt
    \item $\left\{ \begin{array} {rcl} 2x + 3y & = & 3 \\ 12x - 15y & = & -4 \end{array} \right.$
    \item $\left\{ \begin{array} {rcl} y & = & 6-x \\ x & = & \dfrac{9}{2} + y \end{array} \right.$
    \item $\left\{ \begin{array} {rcl} x & = & 2y-8 \\ 2x-y & = & 7 \end{array} \right.$
    \item $\left\{ \begin{array} {rcl} \dfrac{3}{5}x - \dfrac{1}{6}y & = & 1 \\[9pt] %% added 9pt 
  \dfrac{1}{5}x + \dfrac{5}{6}y & = & 11 \end{array} \right.$
\end{enumerate}
\end{multicols}
\end{enumerate}

 \end{document}

Answer 2

更新\arraystretch将同时解决这两个问题。它会改变数组中行的高度。因此，选择合适的值将使系统中的分数间距更好。同时，它使所有行的高度相同，因此左列中的项目现在与右列中的项目大小相同，这将根据需要将 (a) 与 (c) 对齐，将 (b) 与 (d) 对齐。

\documentclass[12pt,lettersize]{article}
\usepackage[top=1.25in, bottom=1.05in, left=0.5in, right=0.5in]{geometry}
\usepackage{multicol}
\usepackage{amsmath,amssymb,amsthm}

\renewcommand{\arraystretch}{2.5}

\begin{document}
    \begin{enumerate}
        \item Solve each system of equations algebraically.
        \begin{multicols}{2}
            \begin{enumerate} \itemsep=12pt
                \item $\left\{ \begin{array} {rcl} 2x + 3y & = & 3 \\ 12x - 15y & = & -4 \end{array} \right.$
                \item $\left\{ \begin{array} {rcl} y & = & 6-x \\ x & = & \dfrac{9}{2} + y \end{array} \right.$
                \item $\left\{ \begin{array} {rcl} x & = & 2y-8 \\ 2x-y & = & 7 \end{array} \right.$
                \item $\left\{ \begin{array} {rcl} \dfrac{3}{5}x - \dfrac{1}{6}y & = & 1 \\ \dfrac{1}{5}x + \dfrac{5}{6}y & = & 11 \end{array} \right.$
            \end{enumerate}
        \end{multicols}
    \end{enumerate}
\end{document}

您可能还考虑使用该类exam：

\documentclass{exam}
\usepackage{array}
\usepackage{amsmath}
\usepackage{multicol}

\renewcommand{\arraystretch}{2.5}
\renewcommand{\thechoice}{\alph{choice}}
\renewcommand{\choicelabel}{(\thechoice)}

\begin{document}

    \begin{questions}
        \question Solve each system of equations algebraically.
        \begin{multicols}{2}
        \begin{choices} 
            \choice $\left\{ \begin{array} {rcl} 2x + 3y & = & 3 \\ 12x - 15y & = & -4 \end{array} \right.$
            \choice $\left\{ \begin{array} {rcl} y & = & 6-x \\ x & = & \dfrac{9}{2} + y \end{array} \right.$
            \choice $\left\{ \begin{array} {rcl} x & = & 2y-8 \\ 2x-y & = & 7 \end{array} \right.$
            \choice $\left\{ \begin{array} {rcl} \dfrac{3}{5}x - \dfrac{1}{6}y & = & 1 \\ \dfrac{1}{5}x + \dfrac{5}{6}y & = & 11 \end{array} \right.$
        \end{choices}
        \end{multicols}
    \end{questions}

\end{document}

Answer 3

也许tabular这里更可行：

% arara: pdflatex

\documentclass[12pt,lettersize]{article}
\usepackage[top=1.25in, bottom=1.05in, left=0.5in, right=0.5in]{geometry}
\usepackage{mathtools}
\usepackage{booktabs}
\usepackage{array}
\makeatletter
\newcases{mycases}{\quad}{%
    \hfil$\m@th\displaystyle{##}$}{$\m@th\displaystyle{##}$\hfil}{\lbrace}{.}
\makeatother

\begin{document}    
\begin{enumerate}       
    \item you could also do:

    %\begin{center} % optional
        \begin{tabular}{%
                l
                >{$}p{7.82cm}<{$} % or optional just ">{$}l<{$}"
                l
                >{$}l<{$}
                }
            (a) & 
            \begin{mycases}
            2x + 3y &= 3 \\ 12x - 15y &=  -4
            \end{mycases} & 
            (b) &
             \begin{mycases}
                y & = 6-x \\ x & = \dfrac{9}{2} + y
             \end{mycases} \\\addlinespace
            (c) & 
            \begin{mycases}
                x &= 2y-8 \\ 2x-y &= 7
            \end{mycases} & 
            (d) &
            \begin{mycases}
                \dfrac{3}{5}x - \dfrac{1}{6}y &= 1 \\ \dfrac{1}{5}x + \dfrac{5}{6}y &= 11
            \end{mycases}            
        \end{tabular}
    %\end{center} % optional
\end{enumerate}
\end{document}