Question

Factorise the following:

a² – 25 – ab + 5b

Answer 1

Given: a² – 25 – ab + 5b

We know that,

(a + b)(a – b) = a² – b²

Hence,

⇒ a² – 5² – b(a – 5)

⇒ (a – 5)(a + 5) – b(a – 5)

⇒ (a – 5)(a + 5 – b)