x2+x+7=0x^{2}+x+7=0x2+x+7=0
x2−x+7=0x^{2}-x+7=0x2−x+7=0
x2−x−7=0x^{2}-x-7=0x2−x−7=0
x2+x−7=0x^{2}+x-7=0x2+x−7=0