等差数列{an}前n项和为Sn,等差数列{bn}前n项和为Tn,而且SnTn=nn+1,则a10b9•a9b10等于()A.1B.323360C.37360D.81100-数学

题目简介

等差数列{an}前n项和为Sn,等差数列{bn}前n项和为Tn,而且SnTn=nn+1,则a10b9•a9b10等于()A.1B.323360C.37360D.81100-数学

题目详情

等差数列{an}前n项和为Sn,等差数列{bn}前n项和为Tn,而且
Sn
Tn
=
n
n+1
,则
a10
b9
a9
b10
等于(  )
A.1B.
323
360
C.
37
360
D.
81
100
题型:单选题难度:中档来源:不详

答案

∵等差数列{an}{bn}的前n项和分别为Sn,Tn,
Sn
Tn
=class="stub"n
n+1

a10
b9
a9
b10
=
a9
b9
a10
b10
=
s17
T17
s19
T19
=class="stub"17
18
×class="stub"19
20
=class="stub"323
360

故选B.

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