Question

factorize this pls..

Answer 1

(x2-4x)(x2-4x+1)-20
=a(a-1)-20 [x2-4x=a has taken]
=a2-a-20
=a2-5a+4a-20
=a(a-5)+4(a-5)
= ( a-5) ( a-4)
=(x2-4x-5)(x2-4x-4) [values are inputed]
=(x2-5x+x-5)(x2-4x-4)
=x(x-5)+1(x-5) (x2-4x-4)
=(x-5)(x+1)(x2-4x-4)

hope it can help!!!

Answer 2

See in the picture attached