Question

行列式（determinant）是多少啊?

Answer 1

2-r1,r3+r1,r4+r1

1 1 -3 1

0 -1 4 3

0 4 -3 2

0 1 -5 -4

r3+4r2,r4+r2

1 1 -3 1

0 -1 4 3

0 0 13 14

0 0 -1 -1

r3+19r4

1 1 -3 1

0 -1 4 3

0 0 0 1

0 0 -1 -1

r3r4 D = (-1)*

1 1 -3 1

0 -1 4 3

0 0 -1 -1

0 0 0 1

所以 D = -1.