已知等比数列前n项和为sn,a1+a3=5,s4=15.1.求数列的通项公式2.设bn=5/2+log2an,tn=?3.求使不等式tn>6成立的最小自然数n的值

已知等比数列前n项和为Sn,a1a2a3...a*n=Pn,1/a1+1/a2+1/a3+...+1/an.求证：（Pn)^2=(Sn/Tn)^n 等比数列{an}中,前n项和为sn,已知S1,S3,S2成等差数列,求{an}的公比Q.已知a1-a3=3,求sn? 等比数列{an}中,前n项和为sn,已知S1,S3,S2成等差数列,求{an}的公比Q.已知a1-a3=3,求sn?RT. 设等比数列{an}的前n项和为Sn.已知a2=6,6a1+a3=30,求an和Sn 设等比数列{an}前n项和为Sn已知a2=6,6a1+a3=30求an和sn 设等比数列{an}的前n项和为Sn,已知a2=6,6a1+a3=30,求an和Sn. 等比数列｛an｝的前n项和为Sn,已知a2=6,6a1+a3=30,求an和Sn? 设等比数列[An]的前n项和为Sn,已知A2=6.6A1+A3=30求An和Sn.急 设数列的前n项和为Sn,已知a1+2a2+3a3+……+nan=(n-1)Sn+2n（n属于N+）(1)求a2,a3的值(2)求证{Sn+2}是等比数列 等比数列｛an｝的前n项和为Sn,已知S1,S3,S2成等差数列.①求公比q②a1-a3=3,求Sn 等比数列{an}的前n项和为Sn,已知S1,S3,S2成等差数列1 ,求｛an｝的公比q2 ,若a1-a3=3求Sn 等比数列an的前n项和为sn 已知s1 s3 s2成等差数列 求an的公比q 求若a1-a3=3 求sn 1.已知a1,a2,a3,a4成等比数列,且a1=a2+36,a3=a4+4,求a1,a2,a3,a42.等差数列{an}中,前n项和为Sn,a1>0,S12>0,S13 已知{an}是公差不为0的等差数列,a1=1,且a1,a3,a9成等比数列,求数列{2^an}的前n项和Sn 设数列{an}前n项和为Sn,已知a1+2a2+3a3+...+nan=(n-1)Sn+2n,（1）求a2,a3的值；（2）求证：数列{Sn+2}是等比数列. 已知数列an的前n项和为sn,且a1=1,a(n+1)=sn(n+2)/n,(n属于正整数)（1）求a2,a3,a4:(2)证明：数列sn/n是等比数列. 已知等比数列{an}的前n项和为Sn,且a3=3/2,S3=9/2,求a1和q 设Sn为等比数列an前n项和,2a3+a4=0,则S3/a1=?3