Question

Log1/9(13-x)=-2 найдите корень уравнения

Answer 1

$log_{ \frac{1}{9}} (13-x)=-2 \\ log_{ \frac{1}{9}} (13-x)=-2log_{ \frac{1}{9}} \frac{1}{9} \\ log_{ \frac{1}{9}} (13-x)=log_{ \frac{1}{9} }81 \\ 13-x=81 \\ x=13-81 \\ x=-68$