3x²+7xy+2y²-5x-5y+2
=(3x+y)(x+2y)-5x-5y+2
=(3x+y-2)(x+2y-1)
x²-2xy-3y²+6x-10y+8
=(x+y)(x-3y)+6x-10y+8
=(x+y+2)(x-3y+4)
2x²+3xy+y²+5x+y-12
=(2x+y)(x+y)+5x+y-12
=(2x+y-3)(x+y+4)
3x²+xy-2y²+6x+y+3
=(3x-2y)(x+y)+6x+y+3
=(3x-2y+3)(x+y+1)