2x2−5x+2=02 x^{2}-5 x+2=02x2−5x+2=0
8x2−5x−1=08 x^{2}-5 x-1=08x2−5x−1=0
2x2+5x+4=02 x^{2}+5 x+4=02x2+5x+4=0
2x2+5x−4=02 x^{2}+5 x-4=02x2+5x−4=0