\(x^2-4xy+4y^2+xz-2yz\)
\(=\left(x^2-4xy+4y^2\right)+\left(xz-2yz\right)\)
\(=\left(x-2y\right)^2+z\left(x-2y\right)=\left(x-2y\right)\left(x-2y+z\right)\)
$#flo$
`x^2 - 4xy + 4y^2 + xz - 2yz`
`= [x^2 -4xy + (2y)^2] + z(x - 2y)`
`= (x-2y)^2 + z(x - 2y)`
`=(x-2y)(x-2y + z)`