Question

If ${\log }_{11}{\log }_7(5x+7)=0$, then find the value of $x$.

• A. $0$
• B. $11$
• C. $7$
• D. $1$

Answer 1

The correct option is A $0$

${\log }_{11}{\log }_7(5x+7)=0$

$\Rightarrow {\log }_7(5x+7)={11}^0(\because \log ax=b\Rightarrow x=a^b)$

$\Rightarrow {\log }_7(5x+7)=1$

$\Rightarrow 5x+7=7^1$

$\Rightarrow 5x=7-7$

$\Rightarrow x=0$