\(\sqrt{2}.\sqrt{18x}-\sqrt{25x}+\sqrt{24}-\dfrac{1}{\sqrt{2}}.\sqrt{8x}\\ =\sqrt{2.18x}-\sqrt{25x}+\sqrt{24}-\sqrt{\dfrac{8x}{2}}\\ =\sqrt{36x}-\sqrt{25x}+\sqrt{24}-\sqrt{4x}\\ =\sqrt{6^2.x}-\sqrt{5^2x}+\sqrt{3.4^2}-\sqrt{2^2x}\\ =6\sqrt{x}-5\sqrt{x}+4\sqrt{3}-2\sqrt{x}\\ =4\sqrt{3}-\sqrt{x}\left(x\ge0\right)\)