Redirected from 685 BC
Decades: 730s BC 720s BC 710s BC 700s BC 690s BC - 680s BC - 670s BC 660s BC 650s BC 640s BC 630s BC
Significant People
... this means that the parabola described by the quadratic equation touches the x-axis in a single point.) If the discriminant is positive, then there are two different ...