只用初等列变换，将该矩阵化为单位矩阵

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c2-2c3
0 0 1
2 -7 3
-3 11 -4

c2+4c1
0 0 1
2 1 3
-3 -1 -4

c1-2c2
0 0 1
0 1 3
-1 -1 -4

c1*(-1),c2+c1,c3+4c1
0 0 1
0 1 3
1 0 0

c3-3c2
0 0 1
0 1 0
1 0 0

c1<伍碰吵橡->腔碰谈C3
1 0 0
0 1 0
0 0 1

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