ax2+y2−y=0a x^{2}+y^{2}-y=0ax2+y2−y=0
x2+y2+ay=0x^{2}+y^{2}+a y=0x2+y2+ay=0
x2+y2−ay=0x^{2}+y^{2}-a y=0x2+y2−ay=0
x2+ay2+y=0x^{2}+a y^{2}+y=0x2+ay2+y=0