701 BC - King Hezekiah of Judah, backed by Egypt, revolts against king Sennacherib of Assyria. Sennacherib sacks many Palestinian cities, but fails in his attempt to take Jerusalem
... a perfect square trinomial 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, ...