Odpowiedź:
1.
f(x) = x² + 2x - 3
x² + 2x - 3 = 0
a = 1 , b = 2 , c = - 3
Δ = b² - 4ac = 2² - 4 * 1 * (- 3) = 4 + 12 = 16
√Δ = √16 = 4
x₁ = ( - b - √Δ)/2a = (- 2 - 4)/2 = - 6/2 = - 3
x₂ = ( - b + √Δ)/2a = (- 2 + 4)/2 = 2/2 = 1
2.
f(x) = 2(x + 2)(x + 5)
2(x + 2)(x + 5) = 0
x + 2 = 0 ∨ x + 5 = 0
x = - 2 ∨ x = - 5
