我正在写数学作业，矩阵对于页面来说太宽，即使切换到横向也会掉下来。有什么建议可以告诉我如何将矩阵分成两行吗？
\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\begin{document}
\begin{align*}
\begin{pmatrix}
a_{11}(b_{11} + c_{11}) + a_{12}(b_{21} + c_{21}) + ... + a_{1n}(b_{n1} + c_{n1})
& a_{11}(b_{12} + c_{12}) + a_{12}(b_{22} + c_{22}) + ... + a_{1n}(b_{n2} + c_{n2})
& \dots
& a_{11}(b_{1k} + c_{1k}) + a_{12}(b_{2k} + c_{2k}) + ... + a_{1n}(b_{nk} + c_{nk})
\\
a_{21}(b_{11} + c_{11}) + a_{22}(b_{21} + c_{21}) + ... + a_{2n}(b_{n1} + c_{n1})
& a_{21}(b_{12} + c_{12}) + a_{22}(b_{22} + c_{22}) + ... + a_{2n}(b_{n2} + c_{n2})
& \dots
& a_{21}(b_{1k} + c_{1k}) + a_{22}(b_{2k} + c_{2k}) + ... + a_{2n}(b_{nk} + c_{nk}) \\
\vdots & \vdots & \ddots & \vdots \\
a_{m1}(b_{11} + c_{11}) + a_{m2}(b_{21} + c_{21}) + ... + a_{mn}(b_{n1} + c_{n1})
& a_{m1}(b_{12} + c_{12}) + a_{m2}(b_{22} + c_{22}) + ... + a_{mn}(b_{n2} + c_{n2})
& \dots
& a_{m1}(b_{1k} + c_{1k}) + a_{m2}(b_{2k} + c_{2k}) + ... + a_{mn}(b_{nk} + c_{nk})
\end{pmatrix}
\end{align*}
\end{document}
答案1
也许
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\[\renewcommand\arraystretch{2}
\begin{pmatrix}
\sum_{i=1}^n a_{1i}(b_{i1}+c_{i1}) &
\sum_{i=1}^n a_{1i}(b_{i2}+c_{i2}) &
\dots &
\sum_{i=1}^n a_{2i}(b_{ik}+c_{ik}) \\
\sum_{i=1}^n a_{2i}(b_{i1}+c_{i1}) &
\sum_{i=1}^n a_{2i}(b_{i2}+c_{i2}) &
\dots &
\sum_{i=1}^n a_{2i}(b_{ik}+c_{ik}) \\
\vdots & \vdots & \ddots & \vdots \\
\sum_{i=1}^n a_{mi}(b_{i1}+c_{i1}) &
\sum_{i=1}^n a_{mi}(b_{i2}+c_{i2}) &
\dots &
\sum_{i=1}^n a_{mi}(b_{ik}+c_{ik})
\end{pmatrix}
\]
\end{document}