化简(2x+3y)(x-y)-(y+2x)(2x-y)

化简(2x+3y)(x-y)-(y+2x)(2x-y)
化简(2x+3y)(x-y)-(y+2x)(2x-y)

化简(2x+3y)(x-y)-(y+2x)(2x-y)
=2x^2-2xy+3xy-3y^2-(2xy-y^2+4x^2-2xy)
=2x^2+xy-3y^2-4x^2+y^2
=xy-2y^2-2x^2

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