1)log2x=3 2)lg(x-1)=0 3)log2log3x=1

Решение
1)  log₂ x = 3
ОДЗ: x > 0
log₂ x = 3log₂ 2
log₂ x = log₂ 2³
x = 8
2)  lg (x - 1) = 0
ОДЗ: x - 1 > 0, x > 1
x - 1 = 10°
x = 1 + 1
x = 2
3)  log₂ log₃ x = 1
ОДЗ:  x > 0
log₃ x = 2¹
x = 3²
x = 9