log4(x+3)+log 4(x+15)=3
log4(x+3)(x+15)=3 - свойство логарифмов
(x+3)(x+15)=64
x^2 + 18 - 19 = 0
D = 81 + 19 = 100
x1 = -9 + 10 = 1
x2 = -9-10 = -19
ответ: 1; -19
log4(x+3)+log 4(x+15)=3
log4(x+3)(x+15)=3 - свойство логарифмов
(x+3)(x+15)=64
x^2 + 18 - 19 = 0
D = 81 + 19 = 100
x1 = -9 + 10 = 1
x2 = -9-10 = -19
ответ: 1; -19