设等差数列an的前n项和为Sn,若S6=24,S9=63,则S15=

来源：学生作业帮助网编辑：六六作业网时间：2024/11/24 20:03:18

设等差数列an的前n项和为Sn,若S6=24,S9=63,则S15=设等差数列an的前n项和为Sn,若S6=24,S9=63,则S15=设等差数列an的前n项和为Sn,若S6=24,S9=63,则S1

设等差数列an的前n项和为Sn,若S6=24,S9=63,则S15=
设等差数列an的前n项和为Sn,若S6=24,S9=63,则S15=

设等差数列an的前n项和为Sn,若S6=24,S9=63,则S15=
由S6=24得 a1+a6=8,由S9=63得 a1+a9=14和 a5=7
所以a1+a9-（a1+a6）=14-8,
所以a9-a6=6
所以公差d=6÷3=2
又因为 a5=7
所以a15=27,a1=-1.
所以S15=195

设等差数列{an}的前n项和为Sn,若S6/S3=3,则S9/S6=? 设Sn是等差数列an的前n项和,若S3/S6=1/3,则S6/S7=? 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=? 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{an}的前n项和,若S3/S6=1/3,求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S3/S6=1/4,则S6/S12等于? 设等差数列an的前n项和为Sn,若S6=24,S9=63,则S15= 设Sn为等差数列｛an｝的前n项和,若S3=3,S6=24,则a9=( ) 设等差数列｛an｝的前n项和为Sn,且S6 等差数列(an)的前n项和sn,若s6：s3=3,求s9：s6 等差数列an的前n项和为sn若s6/S3=3,则s9/S6=? 设等比数列an的前n项的和为Sn,若S6/S3=3,则S9/S6= 设等比数列an的前n项的和为Sn,若S6/S3=3,则S9/S6= 设等比数列an的前n项和为Sn,若S6/S3=3,则S9/S6= 设等比数列{an}的前n项和为sn,若s6/s3=3,则s9/s6=