Gaokao Math Practice Question
3. (5 分) 等比数列 $\left\{a_{n}\right\}$ 的前 $n$ 项和为 $S_{n}$, 已知 $S_{3}=a_{2}+10 a_{1}, a_{5}=9$, 则 $a_{1}=(\quad)$
- A.$\frac{1}{3}$
- B.$-\frac{1}{3}$
- C.$\frac{1}{9}$
- D.$-\frac{1}{9}$
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