先化简,再求值 2(x^2y+2y^2-xy^2)-(2yx^2-3xy^2+3x^2),其中x=-3,y=2
问题描述:
先化简,再求值 2(x^2y+2y^2-xy^2)-(2yx^2-3xy^2+3x^2),其中x=-3,y=2
答
2(x^2y+2y^2-xy^2)-(2yx^2-3xy^2+3x^2)
=2x²y+4y²-2xy²-2x²y+3xy²-3x²
=4y²-3x²+xy²
=4×4-3×9-3×4
=16-27-12
=-23