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If the first term of the G.P. is 16 and its sum to infinity is 96/17 find the common ratio.

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Question

If the first term of the G.P. is 16 and its sum to infinity is `96/17` find the common ratio.

Sum
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Solution

Given:

First term, a = 16

Sum to infinity, S∞ = `96/17`

Formula for sum to infinity of a G.P.:

`S_∞ = a/(1-r)`, where ∣r∣ < 1

`96/17 = 16/(1-r)`

96(1 − r) = 17 × 16

96 − 96r = 272

−96r = 272 − 96

−96r = 176

`r = -176/96`

`= -11/6`

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Chapter 2: Sequences and Series - Exercise 2.3 [Page 33]

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