A1=1,An 1=2an 1 所以An 1 1 = 2(an 1) 所以an 1是以公比为2的等比数列 余下的不用写了吧 an-1 =5Sn-1 - 3 得到an - an-1 = 5an(n>=2) 得到an = -an-1/4 所以an是以公比为-1/4的等比数列 令n = 1 ,a1 = 5a1 - 3 得a1 = -3/4 所以an = a1 * (-1/4)^(n-1) =3 * (-1/4)^n
数列an满足a1=2,an+1=-1/an+1,
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