x-2 x-1 x-2 x-3
2x-2 2x-1 2x-2 2x-3
3x-3 3x-2 4x-5 3x-5
4x 4x-3 5x-7 4x-3
c1-c4,c2-c4,c3-c4
1 2 1 x-3
1 2 1 2x-3
2 3 x 3x-5
3 0 x-4 4x-3
r2-r1, r3-2r1, r4-3r1
1 2 1 x-3
0 0 0 x
0 -1 x-2 x+1
0 -6 x-7 x+3
r4-6r3
1 2 1 x-3
0 0 0 x
0 -1 x-2 x+1
0 0 -5x+5 -5x-3
r2<->r3, r3<->r4
1 2 1 x-3
0 -1 x-2 x+1
0 0 -5x+5 -5x-3
0 0 0 x
行列式 = x(5x-5).