`x^2-x-2001.2002`
`=x^2-2002x+2001x-2001.2002`
`=x(x-2002)+2001(x-2002)`
`=(x-2002)(x+2001)`.
x2 - x - 2001.2002
= (x2 - 2002x) + (2001x - 2001.2002)
= x(x - 2002) + 2001(x - 2002)
= (x + 2001)(x- 2002)
x2-x-2001.2002
=x2-x-2001(2001+1)
=x2-x-20012-2001
=(x2-20012)-(x+2001)
=(x-2001)(x+2001)-(x+2001)
=(x+2001)(x-2001-1)
=(x+2001)(x-2002)