已知等差数列{an}满足:a3=7,a5+a7=26.{an}的前n项和Sn.求a4及sn

已知等差数列{an}满足:a3=7,a5+a7=26.{an}的前n项和Sn.求a4及sn已知等差数列{an}满足:a3=7,a5+a7=26.{an}的前n项和Sn.求a4及sn已知等差数列{an}

已知等差数列{an}满足a3=7,a5+a7=26{an}的前n项和为Sn求a4及Sn已知等差数列{an}满足a3=7,a5+a7=26{an}的前n项和为Sn求a4及Sn已知等差数列{an}满足a3

已知等差数列｛an},a3=7.a5+a7=26.｛an}的前n项和为Sn.1.求a4及Sn.已知等差数列｛an},a3=7.a5+a7=26.｛an}的前n项和为Sn.1.求a4及Sn.已知等差数列

已知等差数列{an}满足：a3=7,a5+a7=26,{an}前n项和为sn,求an及sn已知等差数列{an}满足：a3=7,a5+a7=26,{an}前n项和为sn,求an及sn已知等差数列{an}

已知等差数列{an}满足:a3=7,a5+a7=26.{an}的前n项和为Sn.(1)求an及Sn;(2)令bn=1/an^2-1(n属于N),求数...已知等差数列{an}满足:a3=7,a5+a7

已知等差数列an满足a3=7,a5+a7=26已知等差数列{an}满足:a3=7,a5+a7=26.{an}的前n项和为Sn.(1)求an及Sn;(2)令bn=1/an^2-1(n属于N),求数列{b

已知等差数列｛An｝满足：a3=7,a5+a7=26,｛An｝的前n项和为Sn已知等差数列｛An｝满足：a3=7,a5+a7=26,｛An｝的前n项和为Sn（1）求An及Sn（2）令bn=1/an的2

已知等差数列{an}满足a2+a4=4,a3+a5=10,求{an}的通项公式及{an}的前n项和sn已知等差数列{an}满足a2+a4=4,a3+a5=10,求{an}的通项公式及{an}的前n项和

已知等差数列｛an｝满足：a3=7,a5+a7=26.｛an｝的前n项和为Sn.求令bn=1/(an)^2-1,求｛bn｝及前n项和Tn已知等差数列｛an｝满足：a3=7,a5+a7=26.｛an｝的

已知等差数列(an)满足:a3=7、a5+a7=26、求前n项和Sn已知等差数列(an)满足:a3=7、a5+a7=26、求前n项和Sn已知等差数列(an)满足:a3=7、a5+a7=26、求前n项和

已知等差数列【an】满足:a3=7,a5+a7=26.【an】的前n项和为Sn.(1)求a4及Sn;(2)bn=1/(an^2-1)(n属于N*),求数列【bn】的前n项和Tn已知等差数列【an】满足

等差数列{an}满足:a3=7.a5+a7=26.{an}的前n项和为sn.令bn=1/an^-1（1）求an及sn（2）求数列{bn}的前n项和等差数列{an}满足:a3=7.a5+a7=26.{a

设Sn是等差数列an的前n项和,S7=3(a3+a7),求a5/a4的值设Sn是等差数列an的前n项和,S7=3(a3+a7),求a5/a4的值设Sn是等差数列an的前n项和,S7=3(a3+a7),

已知等差数列｛an｝满足：a3=7,a5+a7=26,an的前n项和为sn.1.求an的通项公式.2.求an的前n项之和sn.已知等差数列｛an｝满足：a3=7,a5+a7=26,an的前n项和为sn

高中数学：等差数列的前n项和!求高手详解已知等差数列{an}满足a3=7,a5+a7=26,{an}的前n项和为Sn.(1)求an及Sn；(2)令bn=1/((an)^2-1)(n€N*)

已知等差数列{an}满足:a3+a4=16,a4+a5=20,{an}的前n项和为Sn(Ⅰ)求Sn(Ⅱ)求数列{1/Sn}的前n项和Tn第一小题会做,已知等差数列{an}满足:a3+a4=16,a4+

已知等差数列｛an｝满足：a3=7,a5+a7=26.｛an｝的前n项和为Sn.（1）、求an及Sn（2）、令bn=1/（an平方）-1（n含于N+）,求数列bn的前N项和Tn.我要图片发到我的邮箱a

已知等差数列｛an｝满足：a3=7,a5+a7=26.｛an｝的前n项和为Sn.（1）、求an及Sn（2）、令bn=1/（an平方）-1（n含于N+）,求数列bn的前N项和Tn已知等差数列｛an｝满足

已知等差数列｛an｝满足：a3＝7,a5＋a7＝26,｛an｝的前n项和为Sn.求an及Sn；令bn＝一除以an的平方减...已知等差数列｛an｝满足：a3＝7,a5＋a7＝26,｛an｝的前n项和为

一道数列题目设等差数列{an}的前n项和为Sn,且满足a2²+a3²=a4²+a5²,S7=7,求数列{an}的通项及前n项和sn一道数列题目设等差数列{an}