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考题(2014年新课标全国卷Ⅱ第17题)已知数列{an}满足a1=1,an+1=3an+1.(1)证明:{an+1/2}是等比数列,并求{an}的通项公式;(2)证明:1/a1+1/a2+...+1/an<3/2.不难证得(1)数列{an+1/2}是以3/2为首项,
(A) Proved that: {an + 1/2} is an isometric sequence, and {a + 1 = 3an + 1} And find {an} general formula; (2) prove: 1 / a1 +1 / a2 + ... + 1 / an <3/2. It is not difficult to prove that the sequence {an + 1/2} is With 3/2 as the first item,