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