A = 2

1 4 1 4 1

2

3 3

4 1 2 2 3 4 1r2-2r1, r3-r1, r4-r1A = 2 1 4 1 0 -1 -6 1 1 3 -3 1 0 2 0 0交換第1,3行A = - 1 3 -3 1 0 -1 -6 1 2 1 4 1 0 2 0 0r3-2r1A = - 1 3 -3 1 0 -1 -6 1 0 -5 10 -1 0 2 0 0r3-5r2, r4+2r2A = - 1 3 -3 1 0 -1 -6 1 0 0 40 -6 0 0 -12 2r3+3r4A = - 1 3 -3 1 0 -1 -6 1 0 0 4 0 0 0 -12 2r4+3r3A = - 1 3 -3 1 0 -1 -6 1 0 0 4 0 0 0 0 2= 1*1*4*2= 8