差数列an的前n项和为sn,a1=1+根号2,s3=9+3根号2

等差数列an的前n项和为sn,a1=1+根号2,s3=9+3根号2 已知等差数列｛an｝的前n项和为sn,a1=1+根号2,S3=9+3倍的根号3求数列的通项公式和前n项和sn,.. 已知等差数列｛an}的前n项之和为Sn,a1=1+根号2.S3=9+3根号2 已知等差数列{ an}的前几项和为Sn,a1=1+根号2 S3=9+3根号2 设 bn=Sn/n(n属于正整数 ) 求证 设数列{an}是首项为a1(a1>0),公差为2的等差数列,前n项和为Sn,且根号S1,根号S2,根号S3成等差数列, 已知数列{an}的前n项和为Sn,a1=1,当n≥2时,an=(根号下Sn+根号下Sn-1)/2 已知Sn是数列{An}的前n项和,A1=2,根号Sn—根号S(n-1)=根号2,求Sn的表达式 等差数列an的前n项和为sn,a1=1+√2 ,s3=9+3√2求数列{an}的通项an与前n项和Sn 已知数列{an}的各项都为正数,a1=1,前n项和Sn满足Sn-Sn-1=根号Sn+根号Sn-1（n≥2),求数列{an 已知Sn是数列An的前n项和,A1=2,根号Sn-根号S(n-1)=根号2 #高考提分#设数列{an}是首项为a1(a1>0),公差为2的等差数列,前n项和为Sn,且根号S1,根号S2,根号S3成 设数列an是首项为a1(a1>0),公差为2的等差数列,其前n项和为Sn,且根号S1,根号S2.根号S3成等差数列.求a