Ответ:
x1 = 3
x2 = -2 + sqrt (21)
x3 = -2 - sqrt (21)
Пошаговое объяснение:
x^2 - 9 = (7 + x) (x^2 - 5x + 6)
x^2 - 9 = 7 x^2 - 35 x + 42 + x^3 - 5 x^2 + 6x
x^2 - 9 = 2 x^2 - 29x + 42 + x^3
-x^2 - 51 + 29x - x^3 = 0
-x^3 + 3 x^2 - 4 x^2 + 12x + 17x - 51 =0
-x^2 (x - 3) - 4x (x - 3) + 17 (x-3) = 0
(x - 3) (x^2 + 4x - 17) = 0
x1 = 3
x2 = -2 + sqrt (21)
x3 = -2 - sqrt (21)