x2+y2−2x+2y+1=0x^{2}+y^{2}-2 x+2 y+1=0x2+y2−2x+2y+1=0
x2+y2−2x+2y+2=0x^{2}+y^{2}-2 x+2 y+2=0x2+y2−2x+2y+2=0
x2+y2−2x+2y−1=0x^{2}+y^{2}-2 x+2 y-1=0x2+y2−2x+2y−1=0
x2+y2−2x+2y=0x^{2}+y^{2}-2 x+2 y=0 x2+y2−2x+2y=0