x^2 + 12x + 6 = -5
x^2 + 12x = -5 - 6
x^2 + 12x = -11
x^2 + 12x + 36 = -11 + 36.....u add 36 to both sides <=
(x + 6)^2 = 25
x + 6 = (+-) sqrt 25
x + 6 = (+-) 5
x = -6 (+-) 5
x = -6 + 5
x = -1
x = -6 - 5
x = -11
solutions are : x = -1 or x = -11
ur answer : add 36 to both sides.. ur x term is 12, take half of ur x term ,which gives u 6, then u square it, which gives u 36...and add that to both sides