Question

Factorise the following:-

4(x2 + 7x)2 – 20(x2 + 7x) (2x – 1) + 25(2x – 1)2

Answer 1

Answer:

(x2+7x)2−8(x2+7x)(2x−1)−15(2x−1)2

=12(x2+7x)2−18(x2+7x)(2x−1)+10(x2+7x)(2x−1)

−15(2x−1)2

=6(x2+7x)[2(x2+7x)−3(2x−1)]+

5(2x−1)[2(x2+7x)+3(2x−1)]

=[2(x2+7x)−3(2x−1)][6(x2+7x)+5(2x−1)]

=[2x2+14x−6x+3][6x2+42x+10x−5]

=(2x2+8x+3)(6x2+52x−5) 

∴12(x2+7