设Sn是等差数列an的前n项和,若S5/S3=5/9,则S9/S5=

来源：学生作业帮助网编辑：六六作业网时间：2025/01/21 16:33:07

设Sn是等差数列an的前n项和,若S5/S3=5/9,则S9/S5=设Sn是等差数列an的前n项和,若S5/S3=5/9,则S9/S5=设Sn是等差数列an的前n项和,若S5/S3=5/9,则S9/S

设Sn是等差数列an的前n项和,若S5/S3=5/9,则S9/S5=
设Sn是等差数列an的前n项和,若S5/S3=5/9,则S9/S5=

设Sn是等差数列an的前n项和,若S5/S3=5/9,则S9/S5=
s5/s3=5(a1+a5)/3(a1+a3)=5a3/3a2=5/9
因此a2=3a3
故公差是a3-a2=-2a3
故a4=a3-2a3=-a3
a5=a4-2a3=-3a3
s9/s5=9(a1+a9)/5(a1+a5)=9a5/5a3=(9/5)*(-3)=-27/5

设Sn是等差数列an的前n项和,若S5/S3=5/9,则S9/S5= 设｛an｝是等差数列前n项和为Sn,若S4>=10,S5 设等差数列an的前n项和为Sn,若S4>=10,S5 设Sn是等差数列an的前n项和,若a5/a3=5/9,则S9/S5= 设sn是等差数列{an}的前n项和,若s9/s5=9/5,则a5/a3= 设等差数列an,的前n项和为Sn,a2+a4=6,求S5 设sn是等差数列an的前n项和,S5=3(a2+a8),则a5/a3的值设Sn是等差数列an的前n项和,a5=5a3,则S9/S5=? 设Sn是等差数列{an}的前n项和,且a1=7,S5=15. 设sn是等差数列an的前n项和 a6/a3=10/7 则s11/s5= 设Sn是等差数列{an}前n项和若a6/a3=2/3 则S11/S5= 设等差数列{An}的前n项和为Sn,若A5=5A3,则S9/S5=? 设等差数列{an}的前n项和为Sn,若a5=5a3,则S9/S5=? 设等差数列｛AN｝的前N项和为SN,若A5=5A3则S9/S5=?. 设等差数列[an]的前n项和为Sn,若a5=5a3,则S9/S5等于多少? 设等差数列an的前n项和为Sn,若a5=5a3,则S9/S5=? 设Sn为等差数列{An}的前n项和,若S5=20 S10=-35则公差为设等差数列{an}的前n项和为Sn,若a5=5a3,则S4/S5