Exercise 20 Page 769

For the addition of two matrices to be possible, they need to have the same dimensions. In our exercise, the first one is a $3\times 2$ matrix. This means it has three rows and two columns. The second one is a $2\times 2$ matrix, so it has two rows and two columns. Because they do not have the same dimensions, the addition is impossible.

$3\times 2$ matrix	$2\times 2$ matrix
$$\begin{array}{c}\left[\begin{array}{cc}\text{-}3& 1\\ 2& \text{-}4\\ \text{-}1& 5\end{array}\right]\end{array}$$	$$\begin{array}{c}\left[\begin{array}{cc}5& 1\\ 0& 2\end{array}\right]\end{array}$$