记 A =
C 0
0 D
则
|A| = |C||D| = -25 * 4 = -100
C^2 =
25 0
0 25
C^4 =
625 0
0 625
D^2 =
4 0
8 4
D^4 =
16 0
64 16
所以 lA^8l = |A|^8 = 100^8 = 10^16.
A^4 =
C^4 0
0 D^4
你自己写吧