题目内容
已知等差数列满足:且,那么公差d=
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A.1 B.2 C.3 D.4
.已知等差数列满足,且数列是等比数列,若,则
A.2 B.4 C.8 D.16
已知等比数列满足,且,,成等差数列,则等于
(A)33 (B)84 (C)72 (D)189
已知等差数列满足,且是此数列的前n项和,则= .