If $\log_{10}{7}=a, then \log_{10}({\frac{1}{70}}) $is equal to:
-(1+a)
$(1+a)^{-1}$
$\frac{a}{10}$
$\frac{1}{10a}$
Explanation:
$\log_{10}({\dfrac{1}{70}})$= $\log_{10}{1}- \log_{10}{70}$
=>$- \log_{10}{7\times 10}$
=>-(a+1)
$\log_{10}({\dfrac{1}{70}})$= $\log_{10}{1}- \log_{10}{70}$
=>$- \log_{10}{7\times 10}$
=>-(a+1)