x²+4y²-2x=4y-2
x²+4y²-2x-4y+2=0
(x-1)^2+(2y-1)^2=0
x=1
y=1/2

（2x-3y）²-(3y-x)²
=(2x-3y-3y+x)(2x-3y+3y-x)
=(3x-6y)x
=3-3
=0