Let’s consider a to be the first term and r to be the common ratio of the G.P.
Given, a = –3
And we know that,
an = arn–1
So, a4 = ar3 = (–3) r3
a2 = a r1 = (–3) r
Then from the question, we have
(–3) r3 = [(–3) r]2
⇒ –3r3 = 9 r2
⇒ r = –3
a7 = a r 7–1 = a r6 = (–3) (–3)6 = – (3)7 = –2187
Therefore, the seventh term of the G.P. is –2187.
Answered by Pragya Singh | 1 year agoConstruct a quadratic in x such that A.M. of its roots is A and G.M. is G.
Find the geometric means of the following pairs of numbers:
(i) 2 and 8
(ii) a3b and ab3
(iii) –8 and –2
Insert 5 geometric means between \( \dfrac{32}{9}\) and \( \dfrac{81}{2}\).