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#958b58bf-66bd-4d68-bd01-b82823b7563f基础填空题等差数列的概念与通项数列

9. 已知等差数列{an}\{a_{n}\}的前nn项和为SnS_{n}3a4a7=73a_{4}-a_{7}=72a7a9=62a_{7}-a_{9}=6,则S10=(S_{10}=(  ))