1) x² - 28x + 147 = 0
x₁ + x₂ = 28 x₁ * x₂ = 147
2(x₁ + x₂) - 4x₁x₂ = 2 * 28 - 4 * 147 = 56 - 588 = - 532
2) x₁² + x₂² = (x₁ + x₂)² - 2x₁x₂ = 28² - 2 * 147 = 784 - 294 = 490
3) x₁³ + x₂³ = (x₁ + x₂)((x₁ + x₂)² - 3x₁x₂) = 28 * (28² - 3 * 147) =
= 28 * (784 - 441) = 28 * 343 = 9604