SATHEE: Sequences and Series 4 Question 7

Sequences and Series 4 Question 7

7.

An infinite GP has first term $x$ and sum 5 , then $x$ belongs to

(2004, 1M)

(a) $x < - 10$

(b) $- 10 < x < 0$

(d) $x > 10$

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Answer:

Correct Answer: 7. (c)

Solution:

We know that, the sum of infinite terms of GP is

$\begin{aligned} S_{\infty} = \frac{a}{1 - r}, | r | < 1 \\ ∴ S_{\infty} = \frac{x}{1 - r} = 5 [| r | < 1] \\ or 1 - r = \frac{x}{5} \\ \Rightarrow r = \frac{5 - x}{5} exists only when | r | < 1 . \\ i.e. - 1 < \frac{5 - x}{5} < 1 \\ or - 10 < - x < 0 \\ \Rightarrow 0 < x < 10 \end{aligned}$

Sequences and Series 4 Question 7

7.

Answer:

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Sequences and Series 4 Question 7

7.

Answer:

Engineering Preparation

Medical Preparation

NCERT Books & Solutions

Important Resources

Other Resources

Syllabus

Test Platform

Sample Mock Test

Mentorship

NCERT Exercise Video Solution

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