1.错.
反例
A =
1 0
0 -1
B =
-1 0
0 1
则有 A^2 = E = B^2,但 A≠B 且 A≠ -B.
2.正确.
|(AB)^k| = |AB|^k = (|A||B|)^k = |A|^k|B|^k = |A^k||B^k|.
1.错.
反例
A =
1 0
0 -1
B =
-1 0
0 1
则有 A^2 = E = B^2,但 A≠B 且 A≠ -B.
2.正确.
|(AB)^k| = |AB|^k = (|A||B|)^k = |A|^k|B|^k = |A^k||B^k|.