∵am-1am+1-2am=0,
由等比數(shù)列的性質(zhì)可得,am2?2am=0
∵am≠0
∴am=2
∵T2m-1=a1a2…a2m-1=(a1a2m-1)?(a2a2m-2)…am
=am2m?2am=am2m?1=22m-1=128
∴2m-1=7
∴m=4
故答案為4
記等比數(shù)列{an}的前n項(xiàng)積為Tn(n∈N*),已知am-1am+1-2am=0,且T2m-1=128,則m=_.
記等比數(shù)列{an}的前n項(xiàng)積為Tn(n∈N*),已知am-1am+1-2am=0,且T2m-1=128,則m=______.
數(shù)學(xué)人氣:284 ℃時(shí)間:2020-04-16 12:19:26
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