(2x+1)^2+y^2+(y-2x)^2=1/34x^2+4x+1+y^2+y^2-4xy+4x^2=1/312x^2+6x+1+3y^2-6xy=0(9x^2+6x+1)+(3x^2-6xy+3y^2)=0(3x+1)^2+3(x-y)^2=03x+1=0,x=-1/3x-y=0,y=x=-1/3x+y=-1/3-1/3=-2/3
