Question

Factorise the following:

1 – a – b + ab

Answer 1

Given expression: 1 – a – b + ab

Step-wise calculation:

1. Rearrange the terms to group them conveniently: 1 – a – b + ab = (1 – a) – (b – ab)

2. Factor out common terms in the grouped parts: (1 – a) – b(1 – a)

3. Notice the common factor (1 – a): (1 – a)(1 – b)

Hence, the factorised form of the expression is (1 – a)(1 – b).