The 5th,9th and 16th terms of a linear sequence A.P are consecutive terms of an exponential sequence.Find the common difference of the linear sequence in terms of the first term.

Answer 1

since the GP has a common ratio,
(a+8d)/(a+4d) = (a+15d)/(a+8d)
(a+8d)^2 = (a+15d)(a+4d)
a^2+16ad+64d^2 = a^2+19ad+60d^2
3ad=4d^2
3a = 4d

Answer 2

Wrong ans

Answer 3

3a+4d