Возведем обе части в квадарат
(4 + x)^2 = 4 - 6x - x^2
x^2 + 8x + 16 = - x^2 - 6x + 4
x^2 + x^2 + 8x + 6x + 16 - 4 = 0
2x^2 + 14x + 12 = 0 /:2
x^2 + 7x + 6 = 0
D = 49 - 24 = 25
x1 = ( - 7 + 5)/2 = - 2/2 = - 1
x2 = ( - 7 - 5)/2 = - 12/2 = - 6
Проверка
4 - 1 = √(4 + 6 - 1)
3 = √9
3 = 3
- 2 = √(4+36-36)
- 2 ≠ 2
Ответ
- 1