x2−5x−6=0x^{2}-5 x-6=0x2−5x−6=0
x2+5x+6=0x^{2}+5 x+6=0x2+5x+6=0
x2−5x+5=0x^{2}-5 x+5=0x2−5x+5=0
x2−5x+6=0x^{2}-5 x+6=0x2−5x+6=0