因为
2x²-3xy-2y²
=(2x+y)(x-2y)
2x²+3x-2
=(2x-1)(x+2)
-2y²+4y-2
=(y-1)(-2y+2
所以
2x²-3xy-2y²+3x+4y-2
=(2x+y-1)(x-2y+2)