The factors of a2+b−ab−a are :
(a−1)(a−b)
Consider the given expression,
a2+b−ab−a......(i)
Rearranging the terms of expression (i), we get
=(a2−ab)+(b−a).....(ii)
Taking a common from first two terms and -1 from last two terms of expression (ii), we get
=a(a−b)−1(a−b)...(iii)
Taking (a−b) common from expression (iii), we get
=(a−b)(a−1)
Therefore , the factors of a2+b−ab−a are (a−b) and (a−1).
i.e., a2+b−ab−a =(a−b)(a−1)