Answer:
| B | = - 9
Step-by-step explanation:
The determinant of a 2 by 2 matrix B = [tex]\left[\begin{array}{ccc}a&b\\c&d\\\end{array}\right][/tex] is
| B | = ad - bc
Then for
B = [tex]\left[\begin{array}{ccc}0&1\\9&8\\\end{array}\right][/tex]
| B | = (0 × 8 ) - (1 × 9 ) = 0 - 9 = - 9
