a: \(=\dfrac{\sqrt{8+2\sqrt{15}}-\sqrt{8-2\sqrt{15}}+2}{\sqrt{2}}\)
\(=\dfrac{\sqrt{5}+\sqrt{3}-\sqrt{5}+\sqrt{3}+2}{\sqrt{2}}\)
\(=\sqrt{6}+\sqrt{2}\)
b: \(=\dfrac{\sqrt{6+2\sqrt{5}}-\sqrt{6-2\sqrt{5}}-2}{\sqrt{2}}\)
\(=\dfrac{\sqrt{5}+1-\sqrt{5}+1-2}{\sqrt{2}}=0\)