Answer:
Step-by-step explanation:
[tex]\left[\begin{array}{ccc}7&31\\142&19\end{array}\right][/tex] = 7(19) - 142(31) = - 4269
[tex]\left[\begin{array}{ccc}7&11&21\\55&-8&2\\-16&-1&-9\end{array}\right][/tex] = 7(- 8)(- 9) + 11(2)(- 16) + 21(55)(- 1) - 21(- 8)(- 16) - 7(2)(- 1) - 11(55)(- 9) = 1768
[tex]\left[\begin{array}{ccc}9.07&6.02&2.01\\-30.7&2.5&3.5\\3.55&-1.1&2.35\end{array}\right][/tex] = 9.07(2.5)(2.35) + 6.02(3.5)(3.55) + 2.01(- 30.7)(- 1.1) - 2.01(2.5)(3.55) - 9.07(3.5)(- 1.1) - 6.02(- 30.7)(2.35) = 647.3561
