因式分解 81(x加y)的平方减121(x减y)的平方

分类: 作业答案 • 2021-12-19 14:58:51

问题描述：

答

81(x+y)^2-121(x-y)^2
=[9(x+y)-11(x-y)][9(x+y)+11(x-y)]
=(9x+9y-11x+9y)(9x+9y+11x-11y)
=(18y-2x)(18x-2y)
=4(9y-x)(9x-y)