If the GP.’s 5,10, 20, .......and 1280, 640, 320, ......have their nth terms equal, find the value of n.
In a finite GP. the product of the terms equidistant from the beginning and the end is always same and equal to the product of first and last term.
If the first and the nth terms of a GP. are a and b respectively and if P is the product of first n terms, prove that P2 = (ab)n.
If show that a, b, c, d are in G.P.
Given
(a + bx) (b - cx) = (a - bx) (b + cx)
or ab - acx + b2x - bcx2 = ab + cax - b2x - bcx2
or b2x + b2x = cax + acx
2b2x = 2acx or b2 = ac or ...(i)
Also,
or or ...(ii)
From (i) and (ii), we have
Hence, a, b, c are in G.P.
If 4th, 10th and 16th terms of a GP. are x, y and z respectively, Prove that y, z are in GP.