In Hinduism, Uma is the goddess of beauty and sunlight. She is an aspect of Devi, and is strongly associated with Parvati (another aspect of Devi). Her cult is centered in Bengal.
... of "=", 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 ...