X^2-x-2 x^2-x-2помогите решить

X^2 - x - 2 = 0 D = b^2  - 4ac = 1 + 8 = 9 = 3^2 x1 = ( 1 + 3)/2 = 2 x2 = ( 1 - 3) / 2 = - 1