r3-2r4,r2+r1,r4-r1 1 1 -1 2 0 0 -5 3 0 0 -14 -3 1 2 4 2 交换行(2次) 1 1 -1 2 1 2 4 2 0 0 -5 3 0 0 -14 -3 = 1 1 * -5 3 1 2 -14 -3 = 1*57 = 57.
