Beforehand

You've probably already seen this problem many times before, but I'm asking you to solve it again. Solve the following equation:

$\large \dfrac{a + \sqrt x}{\sqrt a + \sqrt{a + \sqrt x}} + \dfrac{a - \sqrt x}{\sqrt a - \sqrt{a - \sqrt x}} = \sqrt a$

If $x = ya^2$ , calculate $y$ .