问题描述： 3x^2y-[2xy-2(xy-2/3x^2y)+xy],其中x=3,y=-3/1.等于 1个回答 分类：数学 2014-11-06 问题解答： 我来补答 先化简,再求值3x²y-[2xy-2(xy-2/3x²y)+xy]=3x²y-2xy+2(xy-2/3x²y)-xy=3x²y-2xy+2xy-4/3x²y-xy=5/3x²y-xy=xy(5/3x-1)将x=3,y=-1/3 代入原式=xy(5/3x-1)=3×(-1/3)(5/3×3-1)=-1×(5-1)=-4 展开全文阅读
