Odpowiedź:
2)
x² - 2 (x + 3) = 3
x² - 2x - 6 = 3
x² - 2x - 6 - 3 = 0
x² - 2x - 9 = 0
a = 1, b = - 2, c = - 9
Δ = b² - 4ac = (- 2)² - 4 * 1 * (- 9) = 4 + 36 = 40
x₁ = (- b - √Δ) / 2a = (- (- 2) - √40) /2* 1 = (2 - √40 ) / 2
x₂ = (- b + √Δ) 2a = (2 + √40) / 2
3)
x² - 7x + 12 > 0
x² - 7x + 12 = 0
x = 1, b = - 7, c = 12
Δ = b² - 4ac = (- 7)² - 4 * 1 * 12 = 49 - 48 = 1
√Δ = 1
x₁ = (- b - √Δ) / 2a = (-(- 7) - 1) / 2*1 = (7 - 1) / 2 = 6/2 = 3
x₂ = (- b + √Δ) / 2a = (- (-7) + 1) / 2 * 1 = (7 + 1) / 2 = 8/2 = 4
x ∈ (- ∞ , 3 ) ∪ ( 4 + ∞ )
Szczegółowe wyjaśnienie:
