当x−yx+y=2时,代数式x−yx+y-2x+2y/x−y的值是_.
问题描述:
当
=2时,代数式x−y x+y
-x−y x+y
的值是______. 2x+2y x−y
答
∵
=2,∴x-y=2(x+y),x−y x+y
∴
-x−y x+y
=2x+2y x−y
-2(x+y) x+y
=2-1=1,2(x+y) 2(x+y)
故答案为:1.