Observe the matrix; the matrix has 2 rows and 2 columns.

So, the dimensions of matrix are .

The determinant of a matrix is called a second-order determinant.

Second-order determinant definition is:

Find the determinant using second - order determinant definition.

                            (Multiply: )

                                  (Product of two same signs is positive)

                                         (Add: )

The determinant is  .