\(\left(2\sqrt{3}+\sqrt{5}\right).\sqrt{3}-\sqrt{60}=6+\sqrt{15}-2\sqrt{15}=6-\sqrt{15}\)
\(\left(5\sqrt{2}+2\sqrt{5}\right).\sqrt{5}-\sqrt{250}=5\sqrt{10}+10-5\sqrt{10}=10\)
\(\dfrac{2}{\sqrt{3}-1}-\dfrac{2}{\sqrt{3}+1}=\dfrac{2\sqrt{3}+1-2\sqrt{3}+2}{2}=\dfrac{3}{2}\)
\(\dfrac{x-y}{\sqrt{x}-\sqrt{y}}=\dfrac{\left(\sqrt{x}-\sqrt{y}\right)\left(\sqrt{x}+\sqrt{y}\right)}{\sqrt{x}-\sqrt{y}}=\sqrt{x}+\sqrt{y}\)
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