As a hint, I'll take the determinant of a very similar two by two matrix.
So we wanna figure out the determinant of this matrix and we can denote it
by the determinant of the 2x2 matrix five,
three,negative one and four
and the definition of determinant of the 2x2 matrix like this, as we can first take
this diagonal, five times four
so write it down, just going to be equal to
5 * 4 minus of product of that diagonal
...so what is this
give us? So, five times four is twenty
and then three times negative one will be negative three
this is negative three...
but making negative the negative three will make the positive three
so the determinant of this matrix is twenty three.