等比数列通项公式的性质 (1)对任意的m,n∈N+,an=am· ,q= . (2)若m+n=p+q,则 ,特别地,若m+n=2p,则 . (3)am,am+k,am+2k,am+3k,…仍是等比数列,公比为 . (4)①数列{an}是等比数列,则数列{pan}(p≠0,p是常数)也是等比数列,公比为 . ②若{an}为等比数列,公比为q,则{a2n}也是等比数列,公比为 . ③若{an}为等比数列,公比为q(q≠-1),则{a2n-1+a2n}也是等比数列,公比为 . ④若{an}、{bn}是等比数列,则{anbn}也是等比数列,公比是两等比数列公比之 .
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