Please answer correctly !!!!!!! Will mark brianliest answer !!!!!!!!!!!!!

Answer:
I belive that the correct answer is 32. hope this helps mark me as brianliest????
Step-by-step explanation:
Answer:
missing constant is 36
Step-by-step explanation:
x²-12x+36
because 12x= 2*√x²*√36
so 36 is missing constant
and there is easier way (12/2)² = 36