### Video Transcript

Find the determinant of the
following matrix five, one, negative one, five.

We recall that the determinant of
any matrix is written inside absolute value bars. The determinant of the two-by-two
matrix 𝑎, 𝑏, 𝑐, 𝑑 is equal to 𝑎𝑑 minus 𝑏𝑐. The determinant of the matrix five,
one, negative one, five is equal to five multiplied by five minus one multiplied by
negative one. Five multiplied by five is equal to
25. Multiplying a positive number by a
negative number gives a negative answer. Therefore, one multiplied by
negative one is negative one. We know that subtracting negative
one is the same as adding one. The determinant of the matrix five,
one, negative one, five is therefore equal to 26.