Question

The first three terms of a geometric progression are also the first ninth and eleventh terms respectic of an arithmetic progression.Given that the term of the geometric progression are all difference.find the common ratio(r),If the sum of infinity of the geometric progression is 8.find the first term common difference of the arithmetic progression

Answer 1

Can someone help me to solve it

Answer 2

a, ar, ar^2 are terms of an AP, so we know that
ar-a = 8d
ar^2 - ar = 2d
a/(1-r) = 8
solve for a,r,d and you find
GP: 6, 6/4, 6/16
AP: <b>96/16</b>, 87/16, 78/16, 69/16, 60/16, 51/16, 42/16, 33/16, <b>24/16</b>, 15/16, <b>6/16</b>, ...