Question 866745
1) |-3A| = -3^3 |A| = -27 times -2 =  54
2) A = 2B, |2B| = 2^3 times 5 = 40, then |A| = 40
3) Since A * (adj A) = |A| * I, and A is 3 x 3, we obtain
|A * (adj A)| = |A|^3 = (-3)^3 = -27
-27 = |A * adj A| = |A| |adj A| = -3 |adj A| 
therefore |adj A| = 9
4) |A * (adj A)| = |A|^3 = 12^3 = 1728
5) |A * (adj A)| = |A|^3
|A| |adj A| = |A|^3
|adj A| = |A|^2
8 = |A|^2
2.8284271247461900976 =  |A|