先化简,再求值 2(x^2y+2y^2-xy^2)-(2yx^2-2xy^2+3x^3),其中x=-3,y=2

问题描述:

先化简,再求值 2(x^2y+2y^2-xy^2)-(2yx^2-2xy^2+3x^3),其中x=-3,y=2

2(x^2y+2y^2-xy^2)-(2yx^2-2xy^2+3x^3)
=2x^2y+4y^2-2xy^2-2x^y+2xy^2-3x^3
=4y^2-3x^3
=4*2^2-3*(-3)^3
=16+81
=97还有原式