Решительно уравнение (2 х+3) ^2 = (-х-7) ^2

4x^2 + 12x + 9 = x^2 + 14x + 49

4x^2 + 12x + 9 - x^2 - 14x - 49 = 0

3x^2 - 2x - 40 = 0

D = 4 + 4*3*40 = 4 + 480 = 484 = 22^2

x₁ = (2 + 22) / 6 = 24/6 = 4;

x₂ = (2 - 22) / 6 = - 20/6 = - 10/3 = - 3 целых 1/3