2XA^(-1) = 2E - X, 右乘 A,得 2X = 2A - XA,
X(2E-A) = 2A, X = 2A(2E-A)^(-1),
2E - A =
[ 1 2 0]
[-1 -1 0]
[0 0 1]
(2E - A)^(-1) =
[-1 -2 0]
[ 1 1 0]
[0 0 1]
X = 2A(2E-A)^(-1) =
[-6 -8 0]
[ 4 2 0]
[0 0 2]