Question

Решите уравнение:
lg (7x–5) = 2

Answer 1

$lg (7x-5) = 2$

ОДЗ:

$7x-5>0$

$7x>5$

$x>\frac{5}{7}$

$lg (7x-5) = lg10^2$

$lg (7x-5) = lg100$

$7x-5 = 100$

$7x= 105$

$x=15$

Ответ: $15$