x2−4x+1=0x^{2}-4 x+1=0x2−4x+1=0
x2+4x+1=0x^{2}+4 x+1=0x2+4x+1=0
x2−2x+1=0x^{2}-2 x+1=0x2−2x+1=0
x2−2x+7=0x^{2}-2 x+7=0x2−2x+7=0