Решите уравнение x4 = (3x − 10)2.
Источник: Ященко ОГЭ 2025 (36 вар.)
Решение:
x4 = (3x − 10)2
x4 – (3x – 10)2 = 0
x2⋅2 – (3x – 10)2 = 0
(x2)2 – (3x – 10)2 = 0
(x2 – (3x – 10)) ⋅ (x2 + (3x – 10)) = 0
(x2 – 3x + 10) ( x2 + 3x – 10) = 0
x2 – 3x + 10 = 0
D = (-3)2 – 4 ⋅ 1 ⋅ 10 = -31 (нет корней)
x2 + 3x – 10 = 0
D = 32 – 4 ⋅ 1 (-10) = 49
√49 = 7
x1 = -3 + 7 / 2 = 4/2 = 2
x2 = -3 – 7 / 2 = -10/2 = -5
Ответ: -5; 2