Let the A.P. be a,a+d,a+2d,.....
Given, (a+d).(a+8d)=(a+4d)2
a2+9ad+8d2=a2+8ad+16d2
8d2−ad=0
d[8d−a]=0
∵ d=0
d=8a
So, 2nd term, 5th term, 9th term
would be (a+8a), (a+2a), (a+a)
89a, 23a, 2a
Common Ratio =1stterm2ndterm=2×9a3a×8=34
If the 2nd,5th and 9th terms of a non-constant arithmetic progression are in geometric progression, then the common ratio of this geometric progression is
Held on 3 Apr 2016 · Verified 6 Jul 2026.
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