1 |
2 |
1 |
a |
A.①③ | B.②③ | C.①② | D.③④ |
1 |
2 |
1 |
2 |
1 |
a |
1 |
a |
1 |
a |
1 |
16 |
A.[21,+∞) | B.[9,+∞) | C.[19,+∞) | D.(0,+∞) |
A.若数列{ an}是递增数列,则数列{Sn}也是递增数列: |
B.数列{Sn}是递增数列的充要条件是数列{an}的各项均为正数 |
C.若{an}是等差数列,则对于k≥2且k∈N,S1•S2…Sk=0的充要条件是a1•a2•ak=0 |
D.若{an}是等比数列,则对于k≥2且k∈N,S1•S2…Sk=0的充要条件是ak+ak+1=0. |
© 2017-2019 超级试练试题库,All Rights Reserved.