2010佛山南方杯数学竞赛复赛15题,15、因式分解:x^2y^2-2x^2y+2xy^2+2xy-6x+6y+9

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2010佛山南方杯数学竞赛复赛15题,15、因式分解:x^2y^2-2x^2y+2xy^2+2xy-6x+6y+9

2010佛山南方杯数学竞赛复赛15题,15、因式分解:x^2y^2-2x^2y+2xy^2+2xy-6x+6y+9
2010佛山南方杯数学竞赛复赛15题,
15、因式分解:x^2y^2-2x^2y+2xy^2+2xy-6x+6y+9

2010佛山南方杯数学竞赛复赛15题,15、因式分解:x^2y^2-2x^2y+2xy^2+2xy-6x+6y+9
二楼那不叫因式分解.还有个12.汗
将x看成主元,整理
=y(y-2)x^2+2(y^2+y+6)x+3(2y+3)
然后用十字交叉法化简整理
得到原式=
(xy - 2x+3) (xy + 2y+3)

x^2y^2-2x^2y+2xy^2+2xy-6x+6y+9
=x^2y^2+6xy+9-2x^2y+2xy^2-4xy-6x+6y
=(xy+3)^2-2xy(x-y+2)-6(x-y+2)+12
=(xy+3)^2-2(xy+3)(x-y+2)+12
=(xy+3)(xy+3-2x+2y-4)+12
=(xy+3)(xy-2x+2y-1)+12
=(xy+3)((x+2)(y-2)+3)+12