2x2−x+4=02 x^{2}-x+4=02x2−x+4=0
2x2+x+6=02 x^{2}+x+6=02x2+x+6=0
2x2−x−6=02 x^{2}-x-6=02x2−x−6=0
2x2+9x+4=02 x^{2}+9 x+4=02x2+9x+4=0