1 2 1 3 1 2 1 3 1 2 1 3 1 2 1 3
4 -1 -5 -6 = 0 -9 -9 -18 = 0 1 1 2 = 0 1 1 2
1 -3 -4 -1 0 -5 -5 -4 0 1 1 4/5 0 0 0 1
∴矩阵的秩=3