x2+6x−13=0x^{2}+6 x-13=0x2+6x−13=0
x2+6x+9=0x^{2}+6 x+9=0x2+6x+9=0
x2+6x+13=0x^{2}+6 x+13=0x2+6x+13=0
x2−6x+13=0x^{2}-6 x+13=0x2−6x+13=0