Unfortunately, the package I was expecti

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问题选择题

Unfortunately, the package I was expecting was _____ to the wrong address. [ ]

A. written

B. given

C. packed

D. delivered

答案

答案：D

解答题

设数列{a_n}的各项都是正数，且对任意n∈N⁺，都有a₁³+a₂³+a₃³+…+a_n³=S_n²，其中S_n为数列{a_n}的前n项和．

（Ⅰ）求证：a_n²=2S_n-a_n；

（Ⅱ）求数列{a_n}的通项公式；

（Ⅲ）设b_n=3ⁿ+（-1）^n-1λ•2^a_n（λ为非零整数，n∈N^*）试确定λ的值，使得对任意n∈N^*，都有b_n+1＞b_n成立．

问答题简答题

明四家是指？