|4x-2y-3|+(x+2y-7)的二次方=0
|4x-2y-3|=0
(x+2y-7)^2=0
4x-2y-3=0
x+2y-7=0
5x=10
x=2
y=(7-x)/2=(7-2)/2=2.5
(x-y)^2=(2-2.5)^2=(-0.5)^2=0.25