Theo đề bài, ta có:
(3xy-3x3y+xy3-x2y2) - P = xy-2x2y2+2x3y+xy3
=> P = (3xy-3x3y+xy3-x2y2) - (xy-2x2y2+2x3y+xy3)
=>P= 3xy-3x3y+xy3-x2y2-xy+2x2y2-2x3y-xy3
=>P=(3xy-xy)+(-3x3y-2x3y)+(xy3-xy3)+(-x2y2+2x2y2)
=>P= 2xy - 5x3y + x2y2
Ta có
Đa thức P =3xy-3x\(^3\)y + xy\(^3\)-x\(^2\)y\(^2\)
-
xy +2x\(^3\) y + xy\(^3\) -2x\(^2\)y\(^2\)
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2xy-5x\(^3\)y +x\(^2\)y\(^2\)
Ta có : \(3xy-3x^3y+xy^3-x^2y^2-P=xy-2x^2y^2+2x^3y+xy^3\)\(\Rightarrow P=\left(3xy-3x^3y+xy^3-x^2y^2\right)-\left(2x^2y^2+2x^3y+xy^3\right)\)\(\Rightarrow P=3xy-3x^3y+xy^3-x^2y^2-2x^2y^2-2x^3y+xy^3\)\(\Rightarrow P=3xy+(-3x^3y-2x^3y)+(xy^3+xy^3)+(-x^2y^2-2x^2y^2)\)\(\Rightarrow P=3xy-5x^3y+2xy^3-3x^2y^2\)
Vây P = ......