A wrong problem before

Algebra Level 4

$\large{\begin{cases} x^2 + x\sqrt{xy} = 2016 \\ y^2 + y\sqrt{xy} = 252 \end{cases} }$

Let $$x$$ and $$y$$ be positive real numbers satisfying the above system of equations. Evaluate $$x^2-y^2$$.

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