Answer:
a = -36
Explanation:
Here, we want to get the value of a that would make the expression a perfect square
we simply divide the coefficient of x by 2
That would give 12/2 = 6
Now, square this = 6^2 = 36
Since the number we are to add will be positive so we can have a perfect square of the measure (x + 6)^2;
Then a has to be negative for the last number to turn out positive
Thus, a = -36