等差数列的和1+3+5+···+(4n+1)等于
已知等差数列{an}的前N项和为Sn,a1=-2/3,满足Sn+1/Sn+2=an(n大于等于2)
已知等差数列{an}的前N项和为Sn,a1=-2/3,满足Sn+1/Sn+2=an(n大于等于2),
已知等比数列an等于3的n减1次幂和递增的等差数列bn,其中b2等于5,a1+b1,a2+b2,a3+b3成等比数列
已知Sn是无穷等差数列1,3,5...的前n项和,则limSn/S2n的值等于
等差数列5,11...6n-1的和
设Sn是等差数列An的前n项和,若S3/S6=1/3,则S6/S12等于
已知等差数列前三项和为6前八项和为-4.设数列bn等于{4-an)3的n-1次方求sn
等差数列{an},{bn}的前n项和分别为Sn,Tn,若Sn/Tn=2n/3n+1,则an/bn等于多少?
等差数列{an},{bn}的前n项和分别为Sn,Tn,若Sn/Tn=2n/3n+1,则a3/b3等于多少?
已知数列an是等差数列,a2等于3,a5等于6,数列bn的前n项和是Tn,且Tn加二分之一bn等于1
在项数为2n+1的等差数列中,所有奇数项的和为165,所有偶数项的和为150,则n等于( )
(1)已知:等差数列{An}的前n项和为Sn ,且A3=5,S15等于225 .求数列{An}的通项An