See also : Chaparral
External link
more on this biome (http://www.panda.org/about_wwf/where_we_work/ecoregions/global200/pages/habitat/habitat12.htm)
... 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, ...