Methylene Blue, methylthionine chloride or 3,7-bis(dimethylamino)phenothiazin-5-ium chloride is a chemical compound used as a dye and medication for Gram's stain, Wright stain[?], and the treatment of metoxyhemoglobinemia.
... "=", that will make it 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 ...