Упрости выражения и запиши ответы

а) \(\dfrac{1}{\sqrt{5}}-\dfrac{1}{\sqrt{6}}=\) [ ];

б) \(\dfrac{1}{\sqrt{2}}-\dfrac{1}{\sqrt{6}}=\) [ ];

в) \(\dfrac{1}{\sqrt{27}}+\dfrac{1}{\sqrt{48}}=\) [ ];

г) \(\dfrac{1}{\sqrt{12}}+\dfrac{1}{\sqrt{18}}=\) [ ].