Strictly speaking this entry is about communities like villages, towns and cities that do not exist in the world we know. Like fictional countries, most fictional cities resemble either a specific place or present one version of archetypal place.
... 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, ...