论文部分内容阅读
第1点数列的概念及表示(★★★)必做1若数列{a_n}的前n项和为S_n,则下列命题:1若数列{a_n}是递增数列,则数列{S_n}也是递增数列;2数列{S_n}是递增数列的充要条件是数列{a_n}的各项均为正数;3若{a_n}是等差数列(公差d≠0),则S_1·S_2·…·S_k=0的充要条件是a_1·a_2·…·a_k=0;4若{an}是等比数列,则S_1·S_2·…·S_k=0(k≥2,k∈N)的充要条件是a_n+a_n+1=0.其中,正确命题的个数是()A.0 B.1 C.2 D.3牛刀小试
The concept and representation of the first point sequence (★★★) must be 1 if the first n terms of the sequence {a_n} and is S_n, then the following propositions: 1 If the sequence {a_n} is an incremental sequence, the sequence {S_n} is also incremented 2; if {a_n} is an arithmetic sequence (tolerance d ≠ 0), then S_1 · S_2 ··· ···· The necessary and sufficient conditions for S_k = 0 are: a_1 · a_2 ··· · a_k = 0; 4 If {an} is an equal sequence, then S_1 · S_2 · · · S_k = 0 (k≥2, k∈N) The condition is a_n + a_n + 1 = 0. Among them, the correct number of propositions is () A.0 B.1 C.2 D.3 Chopper small test