# X And Y Flying About

Algebra Level 3

$\dfrac {x^{4}+y^{4}}{x^{4}-y^{4}} + \dfrac {x^{4}-y^{4}}{x^{4}+y^{4}}$

If $$\dfrac {x+y}{x-y} + \dfrac {x-y}{x+y} = 1,$$ then the value of the expression above can be expressed as $$\dfrac {a}{b}$$, where $$a$$ and $$b$$ are coprime positive integers.

What is the value of $$a+b$$?

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