已知数列｛lg an｝为等差数列,求证｛an ｝是等比数列已知数列｛lg a

已知数列｛lg an｝为等差数列,求证｛an ｝是等比数列已知数列｛lg a 已知{An}为等差数列,Bn=A3n+1,求证数列Bn为等差数列. 若数列{an},{bn}都是等差数列,s,t 为已知常数,求证数列{ s an+t bn}是等差数列 已知数列{an}为等差数列,求证:{a3n+a3n-1}是等差数列. 已知数列an满足 a1=1/2,an+1=3an/an+3求证1/an为等差数列已知数列an满足 a1=1/2,an+1=3an/an+3求证1/an为等差数列 已知数列{lgan}是首项为3,公差为2的等差数列,求证:{an}是等比数列. 已知数列{an}的前n项和为Sn=n^2-3n,求证：数列{an}是等差数列 已知数列﹛an}的通项公式为4-2n,求证：数列﹛an}是等差数列 已知数列an中,a9=1/7,an+1=an/3an+1,求证数列1/an为等差数列,求an 已知数列{an}满足a1=2,an+1=2an/an+2.求证数列{1/an}是否为等差数列 并求出an (1)已知数列an的前n项和为sn满足sn=an²+bn,求证an是等差数列(2)已知等差数列an的前n项和为sn,求证数列sn/n也成等差数列 已知数列｛An}是各项为正的等比数列,求证｛lgAn}是等差数列 已知在数列中,An=2的(n-1)次,又Bn=lg(3An),求证数列Bn为单调递增数列 已知在数列中,An=2的(n-1)次,又Bn=lg(3An),求证数列Bn为单调递增数列 已知数列an通项公式为an=lg3^n-lg2^（n+1）,求证an是等差数列 已知数列｛lgAn｝是等差数列,求证｛An｝是等比数列 已知数列｛lgAn｝是等差数列,求证｛An｝是等比数列 若{an}和{bn}数列是等差数列,s,t为已知实数,求证{san+tbn}也是等差数列．