11    8
-4     2

3     2
-6    -6

-3    2
-4    -6

10    8
-6    2

-5
-8
3
10

-9
8
3
2

5
-8
3
10

-5
8
3
2

-3     1
7     -1

1     0
1     -4

-4       0
6     -1

not possible because rows do not match columns

2 x 3

3 x 2

6 x 1

1 x 6

Row

Column

20     15    -10
30     -5         0

-20      15     -10
30     -5          0

1        8       3
11     4        5

20     -15     10
-30         5        0  

25
25
5

-25
25
-5

-10
-10
-6

10
10
6

Yes

No

Sometimes

only Mrs. Jordan knows

3x1

1x3

3x3

1x1

They must be square.

The dimensions must be equal.

The determinant can't equal 0.

The column of the 1st must equal the row of the 2nd.