Factorise: z−7+7xy−xyz
z−7+7xy−xyz
=z−7+xy(7−z)
=−7+z+xy(7−z) [Taking xy as common]
=−1(7−z)+xy(7−z)
=(7−z)(−1+xy) [Taking (7−z) as common]
=(7−z)(xy−1) Therefore,z−7+7xy−xyz=(7−z)(xy−1)