问题描述: 化简求值:2xy^2-[3xy^2-2(x^2y-(1/2)xy^2)]-2x^2y其中x=-2/3,y=-1/2 1个回答 分类:数学 2014-11-01 问题解答: 我来补答 2xy^2-[3xy^2-2(x^2y-(1/2)xy^2)]-2x^2y=2xy²-[4xy²-2x²y]-2x²y=2xy²﹣4xy²﹢2x²y﹣2x²y=﹣2xy²=﹣2×﹙﹣2/3﹚﹙﹣1/2﹚=﹣2/3 再问: ﹣2×﹙﹣2/3﹚﹙﹣1/2﹚ (﹣1/2﹚不是平方吗 再答: 漏了 2xy^2-[3xy^2-2(x^2y-(1/2)xy^2)]-2x^2y =2xy²-[4xy²-2x²y]-2x²y =2xy²﹣4xy²﹢2x²y﹣2x²y =﹣2xy² =﹣2×﹙﹣2/3﹚﹙﹣1/2﹚² =1/3 展开全文阅读