Решите неравенство: 1)log7(2-5x) ≤ 2 2) (1/5)^3x+12 = 1/27

Question

Решите неравенство:
1)log7(2-5x) ≤ 2
2) (1/5)^3x+12 = 1/27

Answer 1

1) log7_(2 - 5x) ≤ log7_49;
{2-5x > 0;       {- 5x >  - 2;      {x < 0,4;
  2-5x ≤ 49;       - 5x ≤ 47;        x ≥ - 9,4       x ∈ [-9,4; 0,4).

2) (1/3)^(3x+12) = 1/27;
(1/3)^(3x+12) = (1/3)^3;
3x + 12 = 3;
3x = -9;
 x = - 3