2−2x2−y22-\frac{2}{x^{2}-y^{2}}2−x2−y22
2−2xx2−y22-\frac{2 x}{x^{2}-y^{2}}2−x2−y22x
2x2−y2−2\frac{2 }{x^{2}-y^{2}}-2x2−y22−2
2xx2−y2−2\frac{2 x}{x^{2}-y^{2}}-2x2−y22x−2