Question

.... log 5 0,000064=x ?

Answer 1

$\log_5(0.000064)=\log_5(\frac{64}{10^6})=\log_5(\frac{2^6}{(2\cdot5)^6})=\log_5(\frac{2^6}{2^6\cdot5^6})=$
$\log_5(\frac{1}{5^6})=\log_5(5^{-6})=-6\log_5(5)=-6(1)=-6$