x²-4y²+2x-4y
=（x+2y)(x-2y)+2(x-2y)
=（x-2y)(x+2y+2)
2.用简便方法计算 1.540²×460²+1080×460
=540²+2×540×460+460²
=(540+460)²
=1000²
=1000 000
2.2008²-2007²
=(2008+2007)(2008-2007)
=4015