# Math Help - Expansion and Factorisation of Algebraic Expressions

1. ## Expansion and Factorisation of Algebraic Expressions

A. Factorise completely:

(a) 18x^2 – 24xy + 8y^2

the answer i get is 2(3x+y)^2

but the answer given is 2(3x + 2y)^2

B.Factorise the following:
(a) (x – 4)(x + 1) + 4a – ax

the answer i get is (x-4)(x+1-a)

but the answer given is (x-4)(x-1-a)

2. $18x^2 - 24xy + 8y^2 = 2(9x^2 - 12xy +4y^2)$

3. A.18x^2 – 24xy + 8y^2

=2(9x^2-12xy+4y^2)
=2{(3x)^2-2(3x)(2y)+(2y)^2}
=2(3x-2y)^2

but the answer given is 2(3x + 2y)^2

4. It should be $2(3x - 2y)^2$.