2x2+4x−1=02 x^{2}+4 x-1=02x2+4x−1=0
x2+4x−1=0x^{2}+4 x-1=0x2+4x−1=0
x2−4x+1=0x^{2}-4 x+1=0x2−4x+1=0
x2−4x−1=0x^{2}-4 x-1=0x2−4x−1=0
