问题
填空题
等差数列{an},{bn}的前n项和分别为Sn、Tn,若
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答案
∵在等差数列中S2n-1=(2n-1)•an,
∴a11=
,b11=S21 21
,T21 21
则
=a11 b11
,S21 T21
又∵
=Sn Tn
,2n 3n+1
∴
=S21 T21 21 32
即
=a11 b11 21 32
故答案为:21 32
等差数列{an},{bn}的前n项和分别为Sn、Tn,若
|
∵在等差数列中S2n-1=(2n-1)•an,
∴a11=
,b11=S21 21
,T21 21
则
=a11 b11
,S21 T21
又∵
=Sn Tn
,2n 3n+1
∴
=S21 T21 21 32
即
=a11 b11 21 32
故答案为:21 32