计算（2X^3-3X^2Y-2XY^2)-(x^3-2xy^2+y^3)+(-x^3+3x^2y-y^3)的值,其中,x

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计算（2X^3-3X^2Y-2XY^2)-(x^3-2xy^2+y^3)+(-x^3+3x^2y-y^3)的值,其中,x=1/2,y=1

（2X^3-3X^2Y-2XY^2)-(x^3-2xy^2+y^3)+(-x^3+3x^2y-y^3)
=2x^3-3X^2Y-2XY^2-X^3+2XY^2-Y^3-X^3+3X^2Y-Y^3
=2x^3-X^3-X^3-3X^2Y+3X^2Y-2XY^2+2XY^2-Y^3-Y^3
=-2Y^3
=-2×（1）^3
=-2

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