X 2 + 12x - 28=0 Помогите!!!

Question

X 2 + 12x - 28=0
Помогите!!!

Answer 1

X^2 + 12x - 28 = 0 
D = 144 + 112 = 256
x1 = ( - 12 + 16)/2 = 4/2 = 2
x2 = ( - 12 - 16)/2 = - 28/2 = - 14