Answer:
4 x 1 ( 4 rows and one column)
Explanation:
Recall the definition for order of a matrix: The number of rows times the number of columns.
So, in this case, we are adding matrix A which is 4 rows and 1 column to matrix B which is also of 4 rows and one column, obtaining a third matrix that has also 4 rows and one column:
![\left[\begin{array}{cccc}-9\\0\\3\\-1\end{array}\right] +\left[\begin{array}{cccc}0\\4\\-6\\2\end{array}\right] =\left[\begin{array}{cccc}-9\\4\\-3\\1\end{array}\right]](https://img.qammunity.org/2021/formulas/mathematics/high-school/9mlf0t44euzdvg4weop1gi0mv5l1ci7oqi.png)
The resultant A + B is also of 4 rows and one column