化简求值2(x^2+3y^3-xy^2)-2(x^2y+2y^3)+3(x^3-xy^2+x^2y),其中x=-3,y=2

2025-05-16 02:54:52
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合并同类项
2(x^2+3y^3-xy^2)-2(x^2y+2y^3)+3(x^3-xy^2+x^2y)
=2x^2+6y^3-2xy^2-2x^2y-4y^3+3x^3-3xy^2+3x^2y
=3x^3+2x^2+x^2y-5xy^2+2y^3
带入x=-3 y=2
得3x^3+2x^2+x^2y-5xy^2+2y^3
=3x(-3)^3+2x(-3)^2+(-3)^2x2-5x(-3)x2^2+2x2^3
=-81+18+18+60+16=31