3.2: GP sum to infinity and AP of logarithms

0606/12/F/M/21 — Question 6 · 11 marks

(a)(i)
A geometric progression has first term 1010 and sum to infinity 66.
Find the common ratio of this progression.
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(a)(ii)
Hence find the sum of the first 77 terms, giving your answer correct to 22 decimal places.
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(b)(i)
The first three terms of an arithmetic progression are logx3\log_{x}3, logx32\log_{x}3^{2}, logx33\log_{x}3^{3}.
Find the common difference of this progression.
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(b)(ii)
Find, in terms of nn and logx3\log_{x}3, the sum to nn terms of this progression. Simplify your answer.
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(b)(iii)
Given that Sn=3081logx3S_{n}=3081\log_{x}3, find the value of nn.
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(b)(iv)
Given also that this sum to nn terms is equal to 10271027, find the value of xx.
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