The 4th term of a G.P. is square of its second term, and the first term is -3. Find its 7th term.
a = -1
T4 = (T2)2
Tn = arn-1
∴ a.r3 = (ar)2
r3 = a.r2
⇒ r = a
∴ r =-1
T7 = ar7-1
= (-1).r6
= -1.(-1)6
= -1.