若(x+y)2+|2y-1|=0,则xy-[2xy-3(xy-1)]的值是 _ .
问题描述:
若(x+y)2+|2y-1|=0,则xy-[2xy-3(xy-1)]的值是 ___ .
答
根据题意得:
,
x+y=0 2y-1=0
解得:
.
x=-
1 2 y=
1 2
则xy-[2xy-3(xy-1)]=xy-[2xy-3xy+3]=xy-2xy+3xy-3=2xy-3=2×(-
)×1 2
-3=-31 2
.1 2
故答案是:-3
.1 2