Дискриминант D = b² - 4ac = (-12)² - 4 * 1 * 35 = 144 - 140 = 4.
√D = √4 = 2.
x₁ = (-b - √D) / 2a = (12 - 2) / 2 = 5.
x₂ = (-b + √D) / 2a = (12 + 2) / 2 = 7.