问题描述: 1.5a+3[2b-3(a-b+2c)-(b+c)] 2.4x²-[2x-(x²-2x+3)-2(x²-3x)] 1个回答 分类:数学 2014-09-30 问题解答: 我来补答 5a+3[2b-3(a-b+2c)-(b+c)]=5a+3(2b-3a+3b-6c-b-c)=5a+6b-9a+9b-18c-3b-3c=(5a-9a)+(6b+9b-3b)-(18c+3c)=-4a+12b-21c 4x²-[2x-(x²-2x+3)-2(x²-3x)]=4x²-(2x-x²+2x-3-2x²+6x)=4x²-2x+x²-2x+3+2x²-6x=(4x²+x²+2x²)-(2x+2x+6x)+3=7x²-10x+3 展开全文阅读