$\dfrac{\sqrt[]{x}}{\sqrt[]{x}-1}+$ $\dfrac{3}{\sqrt[]{x}+1}+$ $\dfrac{4-6\sqrt[]{x}}{x-1}$
$=\dfrac{x+\sqrt[]{x}+3\sqrt[]{x}-3+4-6\sqrt[]{x}}{x-1}$
$=\dfrac{x-2\sqrt[]{x}+1}{(\sqrt[]{x}+1)(\sqrt[]{x}-1)}$
$=\dfrac{(\sqrt[]{x}-1)^2}{(\sqrt[]{x}-1)(\sqrt[]{x}+1)}$
$=\dfrac{\sqrt[]{x}-1}{\sqrt[]{x}+1}$
Chúc bạn học tốt !!!!!