x² - 4x + a = 0
x₁ + x₂ = 4
x₁² + x₂² = 16
(x₁ + x₂)² - 2x₁x₂ = 16
4² - 2x₁x₂ = 16
2x₁x₂ = 16 - 16
x₁ * x₂ = 0
a = x₁ * x₂ = 0
a = 0
x² - 4x = 0
x(x - 4) = 0
x₁ = 0
x - 4 = 0 ⇒ x₂ = 4
ответ : a = 0 ; x₁ = 0 ; x₂ = 4
x² - 4x + a = 0
x₁ + x₂ = 4
x₁² + x₂² = 16
(x₁ + x₂)² - 2x₁x₂ = 16
4² - 2x₁x₂ = 16
2x₁x₂ = 16 - 16
x₁ * x₂ = 0
a = x₁ * x₂ = 0
a = 0
x² - 4x = 0
x(x - 4) = 0
x₁ = 0
x - 4 = 0 ⇒ x₂ = 4
ответ : a = 0 ; x₁ = 0 ; x₂ = 4