If a be the A.M. and x, y be the two G.M.'s between b and c, show that
       Â
The sum of first three terms of a G.P. is  and their product is -1. Find the terms.
The product of three numbers in G.P. is 125 and the sum of their products taken in pairs is  Find them.
The sum of three numbers in G.P. is 21 and the sum of their squares is 189. Find the numbers.
Let a, ar, ar2Â be three numbers in G.P.
Since their sum is 56
∴      a + ar + ar2 = 56
     a(1 + r + r2) = 56                                          ...(i)
Â
It is given that if we subtract 1, 7, 21 from the numbers respectively then the resulting numbers form an A.P.
∴   a - 1, ar - 7, ar2 - 21 are in A.P.
 Â
                                   ...(ii)
Dividing (i) by (ii), we getÂ
     Â
           Â
when           r = 2, from (i),Â
∴ Numbers are 8, 8(2), 8(2)2 or 8, 16, 32
When                from (i),Â
∴   Numbers are    or 32, 16, 8