已知数列(An)的前n项和Sn=-1/2(n²)+kn(k属于正整数集)且Sn的最大值为8.(1)确定常数k,求An(2)求数列{(9-2An)/2n} 的前n项和Tn.抱歉,下面的分母是2的n次方,打不出来哎呀
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![已知数列(An)的前n项和Sn=-1/2(n²)+kn(k属于正整数集)且Sn的最大值为8.(1)确定常数k,求An(2)求数列{(9-2An)/2n} 的前n项和Tn.抱歉,下面的分母是2的n次方,打不出来哎呀](/uploads/image/z/3021409-1-9.jpg?t=%E5%B7%B2%E7%9F%A5%E6%95%B0%E5%88%97%EF%BC%88An%EF%BC%89%E7%9A%84%E5%89%8Dn%E9%A1%B9%E5%92%8CSn%EF%BC%9D%EF%BC%8D1%2F2%EF%BC%88n%26%23178%3B%EF%BC%89%EF%BC%8Bkn%EF%BC%88k%E5%B1%9E%E4%BA%8E%E6%AD%A3%E6%95%B4%E6%95%B0%E9%9B%86%EF%BC%89%E4%B8%94Sn%E7%9A%84%E6%9C%80%E5%A4%A7%E5%80%BC%E4%B8%BA8.%EF%BC%881%EF%BC%89%E7%A1%AE%E5%AE%9A%E5%B8%B8%E6%95%B0k%2C%E6%B1%82An%EF%BC%882%EF%BC%89%E6%B1%82%E6%95%B0%E5%88%97%7B%EF%BC%889-2An%EF%BC%89%2F2n%7D+%E7%9A%84%E5%89%8Dn%E9%A1%B9%E5%92%8CTn.%E6%8A%B1%E6%AD%89%EF%BC%8C%E4%B8%8B%E9%9D%A2%E7%9A%84%E5%88%86%E6%AF%8D%E6%98%AF2%E7%9A%84n%E6%AC%A1%E6%96%B9%EF%BC%8C%E6%89%93%E4%B8%8D%E5%87%BA%E6%9D%A5%E5%93%8E%E5%91%80)
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