bbb?1?
当n?2时,bn?n?n?1?...?2?b1???
bn?1bn?2b1?2?1n
也满足上式,故bn?n,22123n故Tn??2?3?...?n①2222112n?1n
Tn?2?3?...?n?n?1②22222又b1?
n2?n?nn?1
????...???n,1?2?n?1n?2
①-②,得11111n
Tn??2?3?...?n?n?12222221?1?
1???nn?22?2n???n?1?1?n?11221?2故Tn?2?
n?2
.2n2n2n22
)min?,故??(3)由题意得??2,而(2n?nn?n33
甘肃省天水一中2020-2021学年高二上学期第一学段考试数学(文)试题 PDF版含答案
bbb?1?当n?2时,bn?n?n?1?...?2?b1???bn?1bn?2b1?2?1n也满足上式,故bn?n,22123n故Tn??2?3?...?n①2222112n?1nTn?2?3?...?n?n?1②22222又b1?n2?n?nn?1????...???n,1?2?n?1n?2
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