In a GP `a_(1) = 20 and a_(4) = 540` then r = …………..

In a GP, a_(8) = 192, r=2 then a_(12) = …………

If a_(1), a_(2), a_(3),…….,a_(20) are in AP and a_(1) + a_(20) = 45 , then a_(1) + a_(2) + a_(3)+……+a_(20) is equal to

It a_(1) , a_(2) , a_(3) a_(4) be in G.P. then prove that (a_(2)-a_(3))^(2) + (a_(3) - a_(1))^(2) + (a_(4) -a_(2))^(2) = (a_(1)-a_(4))^(2)

It a_(1) , a_(2) , a_(3) a_(4) be in G.P. then prove that (a_(2)-a_(3))^(2) + (a_(3) - a_(1))^(2) + (a_(4) +a_(2))^(2) = (a_(1)-a_(4))^(2)

In a G.P. a = 81, r = -1/3, a_(3) = ……….

(i) Given a G.P. with a=729 and 7th term 64 find S_(7) . (ii) If {a_(n)} is a G.P. and a_(1)=4,r=5 , find a_(6) and S_(6) .

Consider an A.P. a_(1), a_(2), "……"a_(n), "……." and the G.P. b_(1),b_(2)"…..", b_(n),"….." such that a_(1) = b_(1)= 1, a_(9) = b_(9) and sum_(r=1)^(9) a_(r) = 369 , then

Let a_(1),a_(2),a_(3),a_(4) and a_(5) be such that a_(1), a_(2) and a_(3) are in A.P. a_(2) ,a_(3) and a_(4) are in G.P and a_(3) ,a_(4) and a_(5) are in H.P . Then a_(1) ,a_(3) and a_(5) are in

Let ( a_(n) ) be a G.P. such that ( a_(4))/( a_(6)) =( 1)/( 4) and a_(2) + a_(5) = 216 . Then a_(1) =