Answer:
I'm guessing the question is:
Which value must be added to the expression x^2+12x to make it a perfect-square trinomial?
If so, the answer is 36
If not, sorry...
Step-by-step explanation:
You can get the answer by doing (-b/2a)^2. By doing this you get the c term of a perfect square trinomial.
Steps:
1) (b/2a)^2
2) (12/2[1])^2
3) (12/2)^2
4) (6)^2
5) 36