B2=3×10=30; B3=30×10=300; B4=b4-1×q=B3×q=3000
X₁ = -20
x₂ = 10
(x + 20)(x - 10) = 0
x² + 20x - 10x - 200 = 0
x² + 10x - 200 = 0 D = b²-4ac = 100 + 800 = 900 = 30²
x₁ = (-b+√D)/2a = (-10+30)/2 = 10
x₂ = (-b-√D)/2a = (-10-30)/2 = -20
Ответ: x² + 10x - 200 = 0