Answer:
x^2
Step-by-step explanation:
The formula we should use here is (a+b)^2=a^2+2ab+b^2
Using this we should first squared 36, getting us 6
Then divide -12x by 6, getting us -2x
Then we divide-2x by -1, getting us 2x
Lastly we divide 2x by 2 to get x
x is our original factors, but to fit in the equation, we need to square it