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Question

Question: \[\log_{7}{\log_{7}\sqrt{7(\sqrt{7\sqrt{7}})}} =\]...

log7log77(77)=\log_{7}{\log_{7}\sqrt{7(\sqrt{7\sqrt{7}})}} =

A

3log273\log_{2}7

B

13log371 - 3\log_{3}7

C

13log721 - 3\log_{7}2

D

None of these

Answer

13log721 - 3\log_{7}2

Explanation

Solution

log7log7777=log7log777/8=log7(7/8)\log_{7}{\log_{7}\sqrt{7\sqrt{7\sqrt{7}}}} = \log_{7}{\log_{7}7^{7/8}} = \log_{7}(7/8)

=log77log78=1log723=13log72= \log_{7}7 - \log_{7}8 = 1 - \log_{7}2^{3} = 1 - 3\log_{7}2.