问题补充:
已知;xy/x+y=2,求代数式3x+3y-5xy/-x+3x-y的值.谢谢
答案:
xy=2(x+y)
所以原式=[3(x+y)-5xy]/[-(x+y)+3xy]
=[3(x+y)-5*2(x+y)]/[-(x+y)+3*2(x+y)]
=-7(x+y)/[5(x+y)]
=-7/5
时间:2019-01-08 03:19:10
已知;xy/x+y=2,求代数式3x+3y-5xy/-x+3x-y的值.谢谢
xy=2(x+y)
所以原式=[3(x+y)-5xy]/[-(x+y)+3xy]
=[3(x+y)-5*2(x+y)]/[-(x+y)+3*2(x+y)]
=-7(x+y)/[5(x+y)]
=-7/5
当x=2 时 求代数式(x+y)(x-y)+(x-y)2-(x2-3xy)的值.
2022-03-01