2) \(=6\left(x^2+2xy+y^2\right)=6\left(x+y\right)^2\)
3) \(=2y\left(y^2+4y+4\right)=2y\left(y+2\right)^2\)
4) \(=2\left[\left(x^2+2x+1\right)-y^2\right]=2\left[\left(x+1\right)^2-y^2\right]\)
\(=2\left(x+1-y\right)\left(x+1+y\right)\)
5) \(=16-\left(x^2-2xy+y^2\right)=16-\left(x-y\right)^2\)
\(=\left(4-x+y\right)\left(4+x-y\right)\)