An algebra problem by Norwyn Kah

We can express the given as $x=(\sqrt{5}+\sqrt{3})^6 + (\sqrt{5}-\sqrt{3})^6 - (\sqrt{5}-\sqrt{3})^6$ . Notice that $(\sqrt{5}-\sqrt{3})^6<1$ and that the expansion of $(\sqrt{5}+\sqrt{3})^6 + (\sqrt{5}-\sqrt{3})^6$ is an integer. Adding and subtracting $(\sqrt{5}-\sqrt{3})^6$ gives $y=1-(\sqrt{5}-\sqrt{3})^6$ . We have $x(1-y)=(\sqrt{5}+\sqrt{3})^6(\sqrt{5}-\sqrt{3})^6=\boxed{64}$ .