x2+y2+8x−2y+51=0x^{2}+y^{2}+8 x-2 y+51=0x2+y2+8x−2y+51=0
x2+y2−8x−2y+51=0x^{2}+y^{2}-8 x-2 y+51=0x2+y2−8x−2y+51=0
x2+y2+8x+2y−51=0x^{2}+y^{2}+8 x+2 y-51=0x2+y2+8x+2y−51=0
x2+y2−8x−2y−51=0x^{2}+y^{2}-8 x-2 y-51=0x2+y2−8x−2y−51=0