Đáp án: C = $\sqrt[]{x}-1$
Giải thích các bước giải:
C = ($\frac{\sqrt[]{x}}{\sqrt[]{x}+1}$ - $\frac{1}{1-\sqrt[]{x}}$ - $\frac{2\sqrt[]{x}}{x-1}$)($\sqrt[]{x}$ + 1)
= ($\frac{\sqrt[]{x}.(\sqrt[]{x}-1)}{(\sqrt[]{x}+1)(\sqrt[]{x}-1)}$ + $\frac{\sqrt[]{x}+1}{(\sqrt[]{x}+1)(\sqrt[]{x}-1)}$ - $\frac{2\sqrt[]{x}}{x-1}$)($\sqrt[]{x}$ + 1)
= $\frac{\sqrt[]{x}.(\sqrt[]{x}-1)+\sqrt[]{x}+1-2\sqrt[]{x}}{(\sqrt[]{x}+1)(\sqrt[]{x}-1)}$.($\sqrt[]{x}$ + 1)
= $\frac{(\sqrt[]{x}-1)^{2}}{(\sqrt[]{x}+1)(\sqrt[]{x}-1)}$.($\sqrt[]{x}$ + 1)
= $\sqrt[]{x}-1$