x^2 = x + 2;

x^2 - x - 2 = 0;

D = b^2 - 4 * a * c = (-1)^2 - 4 * 1 * (-2) = 1 + 8 = 9;

x1 = (1 + 3)/2 = 4/2 = 2;

x2 = (1 - 3)/2 = -2/2 = -1.