Which of the following sequences are in G.P.? (vi) 120,60,30,18,…

Which of the following sequences are in G.P.?

(vi) 120,60,30,18,…

Solution :

First term (a)  = 120, common ratio

r  = t2/t1   =  60/120 r  = 1/2

r  = t2/t1   =  30/60 r = 1/2

Since the common ratios are same, it is geometric sequence.