老师,这个行列式用递推法怎么算啊?
来源:学生作业帮 编辑:大师作文网作业帮 分类:数学作业 时间:2024/11/10 11:36:35
老师,这个行列式用递推法怎么算啊?
0 1 0 0…0 0
1 0 1 0…0 0
0 1 0 1…0 0
……
0 0 0 0…1 0
n行n列
0 1 0 0…0 0
1 0 1 0…0 0
0 1 0 1…0 0
……
0 0 0 0…1 0
n行n列
按第1列展开
Dn = (-1)^(2+1) * 1 * (-1)^(1+1) * 1 * Dn-2 = - Dn-2
当 n=2k+1 (奇数) 时
Dn = -Dn-2 = (-1)^2 Dn-4 = ... = (-1)^k D1 = 0
当 n=2k (偶数) 时
Dn = -Dn-2 = (-1)^2 Dn-4 = ... = (-1)^(k-1) D2 = (-1)^k = (-1)^(n/2)
Dn = (-1)^(2+1) * 1 * (-1)^(1+1) * 1 * Dn-2 = - Dn-2
当 n=2k+1 (奇数) 时
Dn = -Dn-2 = (-1)^2 Dn-4 = ... = (-1)^k D1 = 0
当 n=2k (偶数) 时
Dn = -Dn-2 = (-1)^2 Dn-4 = ... = (-1)^(k-1) D2 = (-1)^k = (-1)^(n/2)