Question

fill in the blank to make a perfect square y^2-12y+?

Answer 1

$A\ perfect\ square:(a-b)^2=a^2-2ab+b^2\\\\y^2-12y+?\\\\y^2-2y\cdot6+?\\\\\boxed{y^2-2y\cdot6+6^2=y^2-12y+36}=(y-6)^2$