c1+c2+c3+c4
3 1 1 0
3 1 0 1
3 0 1 1
3 1 1 1
ri-r4,i=1,2,3
0 0 0 -1
0 0 -1 0
0 -1 0 0
3 1 1 1
r1r4,r2r3
3 1 1 1
0 -1 0 0
0 0 -1 0
0 0 0 -1
= 3(-1)^3 = -3.
c1+c2+c3+c4
3 1 1 0
3 1 0 1
3 0 1 1
3 1 1 1
ri-r4,i=1,2,3
0 0 0 -1
0 0 -1 0
0 -1 0 0
3 1 1 1
r1r4,r2r3
3 1 1 1
0 -1 0 0
0 0 -1 0
0 0 0 -1
= 3(-1)^3 = -3.