4. Решить логарифмическое уравнение.

1) log₂(4-x) = 7 → 4-x = 128 → x = -124. 2) log₇(7-x) = log₇(3-x)+1 → (7-x) = 7(3-x) → x = 3/2. 3) lg(x-3)+lg(x-2) = 1-lg5 → (x-3)(x-2) = 10/5 → x = 4.