Cho biểu thức \(B=\frac{1}{\sqrt{x}+1}+\frac{x}{\s...

D

- Hướng dẫn giải

\(B=\frac{1}{\sqrt{x}+1}+\frac{x}{\sqrt{x}-x}\)

\(=\frac{1}{\sqrt{x}+1}+\frac{\sqrt{x}}{1-\sqrt{x}}\)\(=\frac{1-\sqrt{x}+\sqrt{x}(1+\sqrt{x})}{1-x}\)\(=\frac{1+x}{1-x}\)

Với \(x=\frac{\sqrt{2}}{2}\Rightarrow B=\frac{1+\frac{\sqrt{2}}{2}}{1-\frac{\sqrt{2}}{2}}=3+2\sqrt{2}\)