(x+y)(x+y)-9(x-y)(x-y)

来源：学生作业帮编辑：搜狗做题网作业帮分类：数学作业时间：2024/05/25 07:03:20

(x+y)(x+y)-9(x-y)(x-y)要详解

解题思路：利用完全平方公式进行计算
解题过程：
(x+y)(x+y)-9(x-y)(x-y)
=(x+y)²-9(x-y)²
=x²+2xy+y²-9（x²-2xy+y²）
= x²+2xy+y²-9x²+18xy-9y²
=-8x²+20xy-8y²
最终答案：略

{(x,y) |x|+|y| x>y?x:y (x+y) X、Y 1.(x-y)(x+y)+(x-y)+(x+y) |x|+|y| x y x+yy x+y xx+y x y (x-y)³+9(x-y)-6(x-y)² 1、x(x-y)(x+y)-x(x+y)^2 z/(x-y) × y/(x+y) COV(9X+Y,X-Y) 3a(x-y)+9(y-x