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Question

Mathematics Question on Logarithmic Differentiation

If log72=?\log_{7} \,2 = ?, then the value of log49(28)\log_{49}\, \left(28\right) is

A

(2?+1)(2? + 1)

B

(2?+3)(2? + 3)

C

12(2?+1)\frac{1}{2}(2? + 1)

D

2(2?+1)2(2? + 1)

Answer

12(2?+1)\frac{1}{2}(2? + 1)

Explanation

Solution

Given, log72=m\log _{7} 2=m
log49(28)=log72(22×7)\therefore \log _{49}(28) =\log _{7^{2}}\left(2^{2} \times 7\right)
=12[2log74+log77]=\frac{1}{2}\left[2 \log _{7} 4+\log _{7} 7\right]
=12log722+121=\frac{1}{2} \log _{7} 2^2+\frac{1}{2}1

22log72+12\frac{2}{2} log_72+\frac12

m+½

2m+12\frac{2m+1}{2}