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#9e48dfee-a602-49a0-be07-31a2c9425caf简单解答题等比数列的概念与通项数列

13.在递增的等比数列{an}\{a_{n}\}中,a3=9a_{3}=9a2+a4=30a_{2}+a_{4}=30. (1)求数列{an}\{a_{n}\}的通项公式; (2)若bn=log3a2nb_{n}=\log _{3}a_{2n},求数列{bn}\{b_{n}\}的前nn项和SnS_{n}