2x^2+4xy+5y^2-4x+2y+5=(x²+4xy+4y²)+(x²-4x+4)+(y²+2y+1)=(x-2y)²+(x-2)²+(y+1)²=0x-2=0y+1=0x+2y=0x=2,y=-1y^x=(-1)²=1