Odpowiedź:
f(x)= - 2x² - x + 1
a = - 2 , b = - 1 , c = 1
Δ = b² - 4ac = (- 1)² - 4 * (- 2) * 1 = 1 + 8 = 9
√Δ = √9 = 3
x₁ = ( - b - √Δ)/2a = ( 1 - 3)/(- 4) = - 2/(- 4) = 2/4 = 1/2
x₂ = ( - b + √Δ)/2a = (1 + 3)/(- 4) = 4/(- 4) = - 4/4 = - 1
x₁ + x₂ = 1/2 - 1 = - 1/2
