Answer:
is -11,-1}
Step-by-step explanation:
because ince quadratic coefient is 1 (term in front of x^2)
take 1/2 of linear cofient (12) and square it
12/2=6, 6^2=36
add that to both sides
x^2+12x+36=-11+36
factor perfect square
(x+6)^2=25
sqrt both sides and take positiv and negative roots
x+6=+/-5
minus 6 both sides
x=-6+/-5
x=-6+5 or x=-6-5
x=-1 or -11