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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...
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已知数列{a
n}的前n项和S
n=50n-n
2(n∈N
*)
(1)求证{a
n}是等差数列.
(2)设b
n=|a
n|,求数列{b
n}的前n项和T
n(3)求
(
)的值.
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