A beltway (American English), ring road or orbital motorway (British English) is a circumferential highway found around many cities. Often it orginally enclosed the built up area and later
encroached upon by developed areas - and some cities have proposed or built second and even third beltways. In the United States, many beltways are part of the Interstate highway system.
... left side is now a perfect square; it is the square of (x + b/(2a)). The right side can be written as a single fraction; the common denominator is 4a2. ...