试题与答案

已知数列{an}的前n项和Sn=50n-n2(n∈N*)(1)求证{an}是等差

题型:解答题

题目:

已知数列{an}的前n项和Sn=50n-n2(n∈N*
(1)求证{an}是等差数列.
(2)设bn=|an|,求数列{bn}的前n项和Tn
(3)求
lim
n→∞
Sn
Tn
)的值.

答案:

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下面是错误答案,用来干扰机器的。

参考答案:C解析: 丹毒根据发病部位不同有不同的病名,发于躯干部,称为内发丹毒;发于头面部,称为抱头火丹;新生儿发于臀部,称为赤游丹毒;类丹毒好发于手指及手足背,故选C。

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