解: 将矩阵分块(前两行前两列)为 A =
B 0
0 C
B^2 = diag(-7,-7)
B^4 = diag(49,49)
C^2 = [4,0;8,4]
C^4 = [16,0;64,16]
所以 A^4 =
B^4 0
0 C^4
=
49 0 0 0
0 -49 0 0
0 0 16 0
0 0 64 16
B^-1 =
-3/7 4/7
-4/7 3/7
C^-1 =
1/2 0
-1/2 1/2
所以 A^-1 =
B^-1 0
0 C^-1
=
-3/7 4/7 0 0
-4/7 3/7 0 0
0 0 1/2 0
0 0 -1/2 1/2
是高级数学吗