m)
\(\begin{array}{l}
xz - yz - {x^2} + 2xy - {y^2}\\
= (xz - yz) - ({x^2} - 2xy + {y^2})\\
= z(x - y) - {(x - y)^2}\\
= (x - y)(z - x + y)\\
p)
{x^2} + 8x + 15\\
= {x^2} + 3x + 5x + 15\\
= x(x + 3) + 5(x + 3)\\
= (x + 3)(x + 5)\\
k)
{x^2} - x - 12\\
= {x^2} + 3x - 4x - 12\\
= x(x + 3) - 4(x + 3)\\
= (x + 3)(x - 4)
\end{array}\)