i: =x^2+8x-x-8
=(x+8)(x-1)
k: =x^2+x+3x+3
=(x+1)(x+3)
l: =-5x^2+15x+x-3
=(x-3)(-5x+1)
m: =x^4+4x^2+4-4x^2
=(x^2+2)^2-4x^2
=(x^2-2x+2)(x^2+2x+2)
n: =x(x^2-2x+1-y^2)
=x(x-1-y)(x-1+y)
i: =(x-y)(x+y)-5(x-y)
=(x-y)(x+y-5)
k: =5x(x^2-xy-2x+2y)
=5x(x-y)(x-2)