泸州市高2017级第二次教学质量诊断性考试文科数学答案

泸州市高2017级第二次教学质量诊断性考试

数 学（文科）参考答案

一、选择题

题号

答案 D C B B C B A D A D D D 1 2 3 4 5 6 7 8 9 10 11 12 二、填空题： 13．?1； 三、解答题：

17．解：（Ⅰ）当n?1时：2S1?a1?1，所以a1?当n≥2时：2Sn?an?1， ①

··························································· 2分 2Sn?1?an?1?1， ② ·

所以2(Sn?Sn?1)?an?an?1?0， ···························································· 3分 即3an?an?1，所以

14．5；

15．3；

16．32．

1， ················································· 1分 3an1?(n≥2)， ····················································· 4分 an?13所以{an}是首项a1?

11，公比为的等比数列， ······································· 5分 33111······························································ 6分 an??()n?1?()n(n?N*)；

333（Ⅱ）因为{bn}是等差数列，b1?3a1?1，b2?2， ·············································· 7分

所以公差d?1， ·················································································· 8分 ·········································································· 9分 bn?1?(n?1)?1?n， ·

Tn?(a1?b1)?(a2?b2)?????(an?bn) ?(a1?a2?????an)?(b1?b2?????bn)

二诊数学文科参考答案 第1页 共6页