(A,E) =
[1 2 -1 1 0 0]
[3 4 -2 0 1 0]
[5 -4 -1 0 0 1]
行初等变换为
[1 2 -1 1 0 0]
[0 -2 1 -3 1 0]
[0 -14 4 -5 0 1]
行初等变换为
[1 0 0 -2 1 0]
[0 -2 1 -3 1 0]
[0 0 -3 16 -7 1]
行初等变换为
[1 0 0 -2 1 0]
[0 -2 0 7/3 -4/3 1/3]
[0 0 1 -16/3 7/3 -1/3]
行初等变换为
[1 0 0 -2 1 0]
[0 1 0 -7/6 2/3 -1/6]
[0 0 1 -16/3 7/3 -1/3]
则 A^(-1) =
[ -2 1 0]
[-7/6 2/3 -1/6]
[-16/3 7/3 -1/3]
经验证正确.