We perform a synthetic division

#color(white)(aaaa)##8##color(white)(aaaa)##|##color(white)(aaaa)##1##color(white)(aaaa)##-2##color(white)(aaaaa)##-40##color(white)(aaaaaa)##-64#

#color(white)(aaaaaa)##color(white)(aaaa)##|##color(white)(aaa)##color(white)(aaaaaaa)##8##color(white)(aaaaaa)##48##color(white)(aaaaaaaa)##64#

#color(white)(aaaaaaaaaa)#------------------------------------------------------------

#color(white)(aaaa)##color(white)(aaaaaa)##color(white)(aaaaaa)##1##color(white)(aaaaa)##6##color(white)(aaaaaaa)##8##color(white)(aaaaaaaa)##color(red)(0)#

The remainder is #=0#

The quotient is #=x^2+6x+8#

This is factorised as

#x^2+6x+8=(x+2)(x+4)#