Odpowiedź:
2x - 3 = x(x + 7)
2x - 3 = x² + 7x
-x² +2x - 7x - 3 = 0
- x² - 5x - 3 = 0
a = - 1 , b = - 5 , c = - 3
Δ= b² - 4ac = (- 5)² - 4 * (- 1) * ( - 3) = 25 - 12 = 13
√Δ = √13
x₁ = (- b - √Δ)/2a = (5 - √13)/(- 2) = - (√13 - 5)/(- 2) = (√13 - 5)/2
x₂ = (- b + √Δ)/2a = (5 + √13)/(- 2) = - (5 + √13)/2
