Question

I’m confused please help

Answer 1

This is completing the square.

So x^2-6x-12=0

Add 12 to both sides so x^2-6x=12

Now take half the x term and square it. Add this number to both sides.

So x^2-6x+9=12+9

Which is the same as (x-3)^2=21

This is answer 2.