有一列数:0,-3/5,4/5,-15/17,12/13,.那么第九个数为?

问题描述:

有一列数:0,-3/5,4/5,-15/17,12/13,.那么第九个数为?
要算法.....

0,-3/5,4/5,-15/17,12/13,.可化为(1-2/2),-(1-2/5),(1-2/10),-(1-15/17),(1-2/26)通项为X(n)=[(-1)^(n+1)]*[1-2/a(n)]a(n)-a(n-1)=2n-1.a(2)-a(1)=3a(1)=2迭代,得a(n)=(3+2n-1)(n-1)/2+2=n^2-1+2=n^2+1...