x²+4y²=2x+4y-2
x²-2x+1+4y²-4y+1=0
(x-1)^2+(2y-1)^2=0
x-1=0 x=1
2y-1=0 y=1/2
(x-2y)^(1/3)
=(1-1)^(1/3)
=0