x2+4x−7=0x^{2}+4 x-7=0x2+4x−7=0
x2−4x+7=0x^{2}-4 x+7=0x2−4x+7=0
x2−3x+2=0x^{2}-3 x+2=0x2−3x+2=0
x2+3x−2=0x^{2}+3 x-2=0x2+3x−2=0