添加和减去矩阵

例1：

添加矩阵。

$\left[\begin{array}{rr}\hfill 1& \hfill 5.\\ \hfill -4.& \hfill 3.\end{array}\right]+\left[\begin{array}{rr}\hfill 2& \hfill -1\\ \hfill 4.& \hfill -1\end{array}\right]$

首先要注意两个加法物是$2\times 2$矩阵，所以我们可以添加它们。

$\left[\begin{array}{rr}\hfill 1& \hfill 5.\\ \hfill -4.& \hfill 3.\end{array}\right]+\left[\begin{array}{rr}\hfill 2& \hfill -1\\ \hfill 4.& \hfill -1\end{array}\right]=\left[\begin{array}{rr}\hfill 1+2& \hfill 5.+（-1）\\ \hfill -4.+4.& \hfill 3.+（-1）\end{array}\right]$

$=\left[\begin{array}{rr}\hfill 3.& \hfill 4.\\ \hfill 0.& \hfill 2\end{array}\right]$

例2：

减去。

$\left[\begin{array}{rrr}\hfill 4.& \hfill 5.& \hfill 6.\\ \hfill 2& \hfill 3.& \hfill 4.\end{array}\right]-\left[\begin{array}{rrr}\hfill 2& \hfill 4.& \hfill 6.\\ \hfill 1& \hfill 2& \hfill 3.\end{array}\right]$

减去对应的条目。

$\left[\begin{array}{rrr}\hfill 4.& \hfill 5.& \hfill 6.\\ \hfill 2& \hfill 3.& \hfill 4.\end{array}\right]-\left[\begin{array}{rrr}\hfill 2& \hfill 4.& \hfill 6.\\ \hfill 1& \hfill 2& \hfill 3.\end{array}\right]=\left[\begin{array}{rrr}\hfill 4.-2& \hfill 5.-4.& \hfill 6.-6.\\ \hfill 2-1& \hfill 3.-2& \hfill 4.-3.\end{array}\right]$

$=\left[\begin{array}{rrr}\hfill 2& \hfill 1& \hfill 0.\\ \hfill 1& \hfill 1& \hfill 1\end{array}\right]$