高二数学数列题,用叠加法做
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发布时间：2024-12-31 07:09
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热心网友
时间：2024-12-31 07:26
(3)
a(n+1)= [(n+1)/n] an
a(n+1)/an =(n+1)/n
an/a(n-1)=n/(n-1)
an/a1 = (2/1)(3/2)...(n/(n-1))
= n
an = n
(4)
nan=(n-1) a(n-1)
an/a(n-1) = (n-1)/n
an/a1 = (1/2)(2/3)...[(n-1)/n]
=1/n
an = 2/n
