\(\dfrac{2}{\sqrt{2}-1}+\sqrt{2}-\sqrt{18}\)
\(=2.\left(\sqrt{2}+1\right)+\sqrt{2}-3\sqrt{2}\)
\(=2\sqrt{2}+2+\sqrt{2}-3\sqrt{2}\)
\(=2\)
\(\dfrac{2}{\sqrt{2}-1}+\sqrt{2}-\sqrt{18}=\dfrac{2}{\sqrt{2}-1}+\sqrt{2}-3\sqrt{2}=\dfrac{2}{\sqrt{2}-1}-2\sqrt{2}=\dfrac{2-2\sqrt{2}\left(\sqrt{2}-1\right)}{\sqrt{2}-1}=\dfrac{2-4+2\sqrt{2}}{\sqrt{2}-1}=\dfrac{-2+2\sqrt{2}}{\sqrt{2}-1}.\)