Redirected from 687 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
... of the form x2 + 2xy + y2. Since "2xy" in this case is (b/a)x, we must have y = b/(2a), so we add the square of b/(2a) to both sides, ...