已知等差数列前n项和为Sn,若Sn=17,求a3+a5

已知数列{an}是等差数列,它的前n项和为Sn.a1+a2+a3=4,a3+a4+a5=10.求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和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},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}满足：a3=7，a5+a7=26，{an}的前n项和为Sn．求an及Sn． 已知等差数列｛An｝满足：a3=7 ,a5+a7=26 ,｛An｝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. 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+a4=16,a4+a5=20,{an}的前n项和为Sn 已知等差数列,a2^2+a3^2=a4^2+a5^2,S7=7 求前n项和Sn 已知等差数列{an}前n项和为Sn,若a4=18-a5,S8等于