等差数列A3=4,A1=A6+2求A1

在等差数列{a}中,a1+a10=2,求a1-a2+a3-a4+a5+a6-a7+a8-a9+a10 等差数列,a6=a3+a8,则,a1+a9=? A1+A3+A5+A7=4,求A2+A4+A6 等差数列an中a1+a2=39 a3+a4=33求a5+a6 等差数列{an}中a1+a2+a3=27 a6+a7=36 求an与Sn 等差数列a1+a6=9,a4=7,求a3,a9 若数列a1,a2…a10为等差数列,s10=140,a1+a3+a5+a7+a9=125,求a6 已知等比数列an中a1+a3=10 a4+a6=5/4求an.证明lg(an)为等差数列 等差数列d=2,a1+a4+a7+```a97=50,a3+a6+a9```+a99=? 等比数列an中,a1,1/2a3,2a2等差数列,a8+a9/a6/a7=? 已知an是等比数列,如果lim（a1+a2+```+an）=2,且a3,a5,a6成等差数列,则a1 已知等差数列an中,a1+a3+a5=21,a2+a4+a6=27,Sn=4Sn=3bn-a1 求an,bn