Answer:
+ 36
Step-by-step explanation:
assuming you require to make the terms into a perfect square.
using the method of completing the square
add ( half the coefficient of the y- term )² to y² - 12y
y² + 2(- 6)y + (- 6)²
= y² - 12y + 36
= (y - 6)² ← a perfect square
