已知xy/x+y=3,求代数式2x-5xy+2y/x-3xy+y

分类: 作业答案 • 2021-12-19 10:55:24

问题描述：

答

xy/x+y=3
则xy=3(x+y)
2x-5xy+2y/x-3xy+y
=2(x+y)-5xy/(x+y)-3xy
=2(x+y)-15(x+y)/(x+y)-9(x+y)
=-13(x+y)/-8(x+y)
=13/8