Log5•(x2-2x)=log5•(2x+12)

ОДЗ
x ∈ ( - 6; 0) ∪(2; + ∞)

x^2  - 2x = 2x + 12
x^2 - 4x - 12 = 0 
D = 16 + 48 = 64 = 8^2
x1 = ( 4 + 8)/2 = 12/2 = 6;
x2 = ( 4 -  8)/2 = - 4/2 = - 2;

Ответ
- 2; 6