X⁴ + 7x³ - 15x² - 175x - 250 = 0
x⁴ + 7x³ - 25x² + 10x² - 175x - 250 = 0
x⁴ - 25x² + 7x³ - 175x + 10x² - 250 = 0
x²(x² - 25) + 7x(x² - 25) + 10(x² - 25) = 0
(x² -25)(x² + 7x + 10) = 0
x² - 25 = 0
x² = 25
x = ±5
x² + 7x + 10 = 0
D = 49 - 40 = 9
x₁ = (-7 + 3)/2 = -2
x₂ = (-7 - 3)/2 = -5
Ответ: -5, -2, 5