题目

已知{an}是等差数列,且公差d≠0,又a1,a2,a4依次成等比数列,则a1+a4+a10/a2+a4+a7=
求解答过程,写的详细些,谢谢了.

提问时间：2020-10-15

答案

∵{an}是等差数列∴a2=a1+da4=a1+3d∵a1,a2,a4依次成等比数列∴(a2)^2=a1*a4即（a1+d)^2=a1(a1+3d)a1^2+2a1+d^2=a1^2+3a1da1d=d^2∵公差d≠0,∴a1=d∴a4=4a1 a7=7a1 a10=10a1 a2=2a1式子要是有括号是（a1+4a1+10a1）...