81(x+y)^4-16(x+y)^4

分类: 作业答案 • 2022-02-06 08:55:36

问题描述：

81(x+y)^4-16(x+y)^4

答

81(x+y)^4-16(x+y)^4
=[9(x+y)^2]^2-[4(x+y)^2]^2
=[9(x+y)^2+4(x+y)^2][9(x+y)^2-4(x+y)^2]
=13(x+y)^2*5(x+y)^2
=65(x+y)^2