You can write the dimensions of a matrix when you write the number of horizontal rows and the number of vertical columns of the matrix in that order.
Notice that to find the number of rows, count from top to bottom or from bottom to top.
To find the number of columns, count from left to right or from right to left.
Example #1:
Write the dimensions of the following matrix:
| 2 | -8 | 0 |
| 7 | 3 | -3 |
| 6 | 0 | 1 |
The matrix above has 3 rows and 3 columns, so the dimensions of this matrix is 3 rows x 3 columns.
You can also say that the matrix is a 3 x 3 matrix.
A matrix that has the same number of rows and columns is called a square matrix. The matrix in example #1 is then a square marix.
Example #2:
Write the dimensions of the following matrix:
[ -4 1 9 ]
The matrix above has 1 row and 3 columns, so the dimensions of this matrix is 1 row x 3 columns.
You can also say that the matrix is a 1 x 3 matrix.
Example #3:
Write the dimensions of the following matrix:
| 2 |
| 0 |
| 7 |
| 4 |
The matrix above has 4 rows and 1 column, so the dimensions of this matrix is 4 rows x 1 column.
You can also say that the matrix is a 4 x 1 matrix.
Example #4:
Write the dimensions of the following matrix:
| 0 | 3 |
| 5 | 5 |
| 1 | 9 |
The matrix above has 3 rows and 2 columns, so the dimensions of this matrix is 3 rows x 2 columns.
You can also say that the matrix is a 3 x 2 matrix.
Example #5:
Write the dimensions of the following matrix:
[ 25 ]
The matrix above has 1 row and 1 column, so the dimensions of this matrix is 1 row x 1 column.
You can also say that the matrix is a 1 x 1 matrix.