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Solution for The 4th Term of a G.P. is Square of Its Second Term, and the First Term is –3. Determine Its 7thterm. - CBSE (Arts) Class 11 - Mathematics

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Question

The 4th term of a G.P. is square of its second term, and the first term is –3. Determine its 7thterm.

Solution

Let a be the first term and r be the common ratio of the G.P.

∴ a = –3

It is known that, an = arn–1

aar3 = (–3) r3

a2 = a r1 = (–3) r

According to the given condition,

(–3) r3 = [­(–3) r]2

⇒ r = –3

a7 = a r 7–1 a r6 = (–3) (–3)6 = – (3)7 = –2187

Thus, the seventh term of the G.P. is –2187.

  Is there an error in this question or solution?

APPEARS IN

 NCERT Solution for Mathematics Textbook for Class 11 (2013 to Current)
Chapter 9: Sequences and Series
Q: 4 | Page no. 192
Solution The 4th Term of a G.P. is Square of Its Second Term, and the First Term is –3. Determine Its 7thterm. Concept: Geometric Progression (G. P.).
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