即(x²-4x+4)+|y-1/2|=0
(x-2)²+|y-1/2|=0
所以x-2=y-1/2=0
x=2,y=1/2
原式=(x²-y²)/xy÷(x+y)
=(x+y)(x-y()/xy÷(x+y)
=(x-y)/xy
=(3/2)/(2×1/2)
=3/2