\(=y\left(x^2+xy-yz-z^2\right)+xz\left(x-z\right)\)
\(=y\left[\left(x-z\right)\left(x+z\right)+y\left(x-z\right)\right]+xz\left(x-z\right)\)
\(=\left(x-z\right)\left(xy+yz+y^2\right)+xz\left(x-z\right)\)
\(=\left(x-z\right)\left(xy+yz+xz+y^2\right)\)
\(=\left(x-z\right)\left(x+y\right)\left(y+z\right)\)