Ta có: \(\left\{{}\begin{matrix}2014-x< 2015-x\\2014-y< 2015-y\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}\sqrt{2014-x}< \sqrt{2015-x}\\\sqrt{2014-y}< \sqrt{2015-y}\end{matrix}\right.\)
\(\Rightarrow\sqrt{2014-x}+\sqrt{2014-y}< \sqrt{2015-x}+\sqrt{2015-y}\)
\(\Rightarrow\dfrac{1}{\sqrt{2014-x}+\sqrt{2014-y}}>\dfrac{1}{\sqrt{2015-x}+\sqrt{2015-y}}\)
\(\Rightarrow\dfrac{1}{\sqrt{2014-x}+\sqrt{2014-y}}-\dfrac{1}{\sqrt{2015-x}+\sqrt{2015-y}}>0\)
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