Gaokao Math Practice Question
4. (5 分) 已知等比数列 $\left\{a_{n}\right\}$ 满足 $a_{1}=3, a_{1}+a_{3}+a_{5}=21$, 则 $a_{3}+a_{5}+a_{7}=(\quad)$
- A.21
- B.42
- C.63
- D.84
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