Question

(x^2-4x)(x^2-4x-1)-20 Factorize by grouping

Answer 1

(x² - 4x )(x² -4x -1) -20

let (x² -4x ) = P


P(P -1) -20

P² -P -20

P² -5P +4P -20

P( P -5) +4 ( P -5)

(P +4 )( P -5)

put P = x² - 4x

(x² -4x +4)( x² - 4x -5)

(x -2)²( x + 1)(x -5)

Answer 2

hi friend,

let x²-4x=y

then the question will be

(y)(y-1)-20

=y²-y-20

=y²-5y+4y-20

=y(y-5)+4(y-5)

=(y+4)(y-5)

by substituting the value of y

=(x²-4x+4)(x²-4x-5)

=(x-2)²(x²-5x+x-5)

=(x-2)²(x(x-5)+1(x-5)

=(x-2)²(x+1)(x-5)



I hope this will help u :)