Discussion of Question with ID = 017 under Logarithms

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Suppose for the sake of this question that $\text"log"_2(7)$ = 14. Then what is $\text"log"_7(128)$?

1/2.

$\text"log"_2(7)$.

$\text"log"_7(2)$.

Soln.
Ans: a

$\text"log"_7(128)$ is same as $\text"log"_7(2^7)$ = 7 × $\text"log"_7(2)$ = $7/{\text"log"_2(7)}$, which is same as $7/14$ = 1/2.