x2+2x+6=0x^{2}+2 x+6=0x2+2x+6=0
x2−2x+6=0x^{2}-2 x+6=0x2−2x+6=0
x2+2x−6=0x^{2}+2 x-6=0x2+2x−6=0
x2−2x−6=0x^{2}-2 x-6=0x2−2x−6=0
