Odpowiedź:
1.
- 12x² + x = 0
x(- 12x + 1) = 0
x = 0 ∨ - 12x + 1 = 0
x = 0 ∨ 12x = - 1
x = 0 ∨ x = - 1/12
2.
3x² - 3 = 0
3(x² - 1) = 0
(x - 1)(x + 1) = 0
x - 1 = 0 ∨ x + 1 = 0
x = 1 ∨ x = - 1
3.
(2x - 5)² - 25 = 0
4x² - 20x + 25 - 25 = 0
4x² - 20x = 0
4x(x - 5) = 0
4x = 0 ∨ x - 5 = 0
x = 0 ∨ x = 5
4.
3x² - 15x = - 18
3x² - 15x + 18 = 0 | : 3
x² - 5x + 6 = 0
a = 1 , b = - 5 , c = 6
Δ = b² - 4ac = (- 5)² - 4 * 1 * 6 = 25 - 24 = 1
√Δ = √1 = 1
x₁ = (- b - √Δ)/2a = (5 - 1)/2 = 4/2 = 2
x₂ = (- b + √Δ)/2a = (5 + 1)/2 = 6/2 = 3
