Question

设S_n为等比数列{a_n}的前n项和，已知，则公比q=

1. A.
   3
2. B.
   4
3. C.
   5
4. D.
   6

Answer 1

B
分析：先将条件化简，再相减，利用等比数列的定义，可求等比数列的公比．
解答：∵
∴3S₂₀₁₂=a₂₀₁₃+ln2，3S₂₀₁₁=a₂₀₁₂+ln2
两式相减可得3a₂₀₁₂=a₂₀₁₃-a₂₀₁₂
∴a₂₀₁₃=4a₂₀₁₂
∴公比q=4
故选B．
点评：本题考查等比数列的求和，考查等比数列的定义，属于中档题．