x^2+y^2-2x+4y+1+4=0(x^2-2x+1)+(y^2+4y+4)=0(x-1)^2+(y+2)^2=0x-1=0x=1y+2=0y=-2
x^2+y^2-2x+4y+5=(x-1)²+(y+2)²=0x-1=0y+2=0x=1y=-2
