x2+y2+2x−2y=62x^{2}+y^{2}+2 x-2 y=62x2+y2+2x−2y=62
x2+y2+2x−y=47x^{2}+y^{2}+2 x-y=47x2+y2+2x−y=47
x2+y2−2x+2y=47x^{2}+y^{2}-2 x+2 y=47x2+y2−2x+2y=47
x2+y2−2x+2y=62x^{2}+y^{2}-2 x+2 y=62x2+y2−2x+2y=62