数列答疑一题设Sn是等差数列{an}的前n项和,若S3/S6=1/3,则S6/S12=______我是把S6,S9,S1
2个回答
s3=3a1+3d
s6=6a1+15d
s3/s6 =1/3
a1=2d
s6= 6a1+15d=27d
s12=12a1+66d= 90d
s6/s12=3/10
相关问题
Sn是等差数列an前n项和,若S3/S6=1/3,则S6/S12=?
设Sn是等差数列An的前n项和,若S3/S6=1/3,则S6/S12等于
设sn是等差数列前n项和,若s3/s6=1/3则s6/s12=?
1.设Sn是等差数列【An]的前n项和,若S3/S6=1/3,求S6/S12
设Sn是等差数列{an}的前n项和,若S3S6=13,则S6S12=( )
设Sn是等差数列{an}的前n项和,若S3S6=13,则S6S12=( )
设Sn是等差数列{an}的前n项和,若S3S6=13,则S6S12=( )
sn是等差数列{an}前n项和,若s3/s6=1/3,求s6/s12
设Sn是等差数列{an}的前N项和,诺S3/S6=1/3则S6/S12=多少
设等差数列{an}的前n项和为Sn,若S6-S3=9,则S9=______.