Factorise the following expression:
x2yz + xy2z + xyz2
∵ x2yz = x × x × y × z = (xyz)[x]
xy2z = x × y × y × z = (xyz)[y]
xyz2 = x × y × z × z = (xyz)[z]
∴ x2yz + xy2z + xyz2 = (xyz)[x + y + z]
= xyz(x + y + z)