Question

log7(49a), если log7a= -8,6

Answer 1

При $\displaystyle a\geq{0}:$
$\displaystyle \log_7(49a)=\log_7(49)+\log_7(a)=2-8.6=\boxed{-6.6}\phantom{.}.$

Answer 2

$\log_7 (7^2 \cdot a)=\log_7 7^2 + \log_7a=2 \log_77 +(-8,6)=2 -8,6=-6,6$