x2+y2+4x−8y+4=0 x^{2}+y^{2}+4 x-8 y+4=0x2+y2+4x−8y+4=0
x2+y2−4x+8y+4=0 x^{2}+y^{2}-4 x+8 y+4=0x2+y2−4x+8y+4=0
x2+y2−4x−8y+4=0x^{2}+y^{2}-4 x-8 y+4=0x2+y2−4x−8y+4=0
x2+y2+4x+8y+4=0 x^{2}+y^{2}+4 x+8 y+4=0x2+y2+4x+8y+4=0