How do you factor completely # 6x^2 + 18xy + 12y^2#?
Always look to see if there is a common factor first.
In this case you can divide out a factor of 6 from all the terms.
Now, the factors of 2 which add up to 3 are 2 and 1.
The signs are the same, they are both positive.
There will be an x and a y term in each bracket.