Mathematics - Functions Question with Solution | TestHub

Out of 4 choices, if

$\mathrm{f}(\mathrm{x})=\frac{1-\mathrm{x}}{1+\mathrm{x}}$. $\mathrm{f}[\mathrm{f}(\mathrm{x})]=\frac{1-\frac{(1-\mathrm{x})}{(1+\mathrm{x})}}{1+\frac{(1-\mathrm{x})}{(1+\mathrm{x})}}=\mathrm{x}$

$\therefore \frac{1-\mathrm{x}}{1+\mathrm{x}}$ is the inverse of itself.