矩阵 A 初等行变换为
[1 2 0 -2 -4]
[0 -1 1 1 1]
[0 -8 8 9 12]
[0 -7 7 8 11]
A 初等行变换为
[1 0 2 0 -2]
[0 1 -1 -1 -1]
[0 0 0 1 4]
[0 0 0 1 4]
A 初等行变换为
[1 0 2 0 -2]
[0 1 -1 0 3]
[0 0 0 1 4]
[0 0 0 0 0]