1 |
bn |
1 |
2 |
1 |
4 |
1 |
6 |
1 |
20 |
n |
2 |
1 |
2 |
1 |
bn+1 |
1 |
bn |
1 |
bn |
1 |
bn |
1 |
n |
1 |
2 |
1 |
3 |
1 |
n |
1 |
2 |
1 |
3 |
1 |
n |
1 |
n+1 |
1 |
2n |
1 |
2 |
1 |
3 |
1 |
n |
1 |
n+1 |
1 |
n+2 |
1 |
2n |
1 |
n+2 |
1 |
n+3 |
1 |
2n+2 |
1 |
n+1 |
1 |
n+2 |
1 |
2n |
1 |
2n+1 |
1 |
2n+2 |
1 |
n+1 |
1 |
2n+1 |
1 |
2n+2 |
1 |
(2n+1)(2n+2) |
n |
2 |
1 |
2 |
1 |
2 |
1 |
2 |
1 |
2 |
k |
2 |
1 |
2 |
1 |
2 |
1 |
2k |
1 |
2k+1 |
k |
2 |
1 |
2k+1 |
1 |
2k+1 |
k |
2 |
| ||||||
2k个 |
k |
2 |
1 |
2 |
k+1 |
2 |
1 |
2 |
1 |
2k |
1 |
2k+1 |
1 |
2 |
1 |
2k+1 |
1 |
2k+1 |
1 |
2 |
| ||||||
2k个 |
1 |
2 |
1 |
3 |
A.一定是等差数列 |
B.一定是等比数列 |
C.或者是等差数列,或者是等比数列 |
D.既不可能是等差数列,也不可能是等比数列 |
1 |
sn-1 |
A.a19>0,a21<0 | B.a20>0,a21<0 |
C.a19<0,a21>0 | D.a19<0,a20>0 |
A.10 | B.15 | C.30 | D.60 |
A.9 | B.10 | C.11 | D.12 |
© 2017-2019 超级试练试题库,All Rights Reserved.