设{an}是公差d不为零的正项等差数列,Sn为其前n项的和,满足5S3-6S5=

题型:解答题

问题:

设{an}是公差d不为零的正项等差数列,Sn为其前n项的和,满足5S3-6S5=-105,a2,a5,a14成等比数列.
(1)求数列{an}的通项公式;
(2)设c∈N,c≥2,令bn=|
an
2c-1
-1|
,Tn为数列{bn}的前n项的和,若T2c≤6,求c的值.
考点:等差数列的通项公式等比数列的定义及性质数列求和的其他方法(倒序相加,错位相减,裂项相加等)
题型:解答题

第二卷(共两节,满分35分)

第一节:短文填词(共10题,每小题1分,满分10分)

People living in different countries made different kinds of words. 

Today there are about fifteen hundred _________ in the world.  76.__________

Each contains many thousands of words. A very large dictionary,

for example, ________(含有) four or five hundred thousand words. 77.__________

But we do not need all these. To r_________short stories, we need   78.__________

to know only about two thousand words_______we leave school.              79 .__________

The words we know are ___________(称为) our vocabulary.           80. __________

We should try to make our vocabulary b______as we continue to study.     81._________

Read as many books as we can. There are a lot of books ________(写)      82. _________

in easy English. We will enjoy them. When we come _____ a new word,     83. _________

look it ________ in our dictionary. Our dictionary is                      84. _________

our __________  (much) useful book.                                85. _________

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A.25℃

B.30℃

C.35℃

D.40℃

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A.in    

B.to    

C.on    

D.that

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B.6个月

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