9(x-y)²-12(y²-x²)+4(x+y)²

分类: 作业答案 • 2022-06-24 18:27:03

问题描述：

答

9(x-y)²-12(y²-x²)+4(x+y)²
＝[3(x-y)]²+2·[3(x-y)]·[2(x+y)]+[2(x+y)]²
＝[3(x-y)+2(x+y)]²
＝(5x-y)².