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