## Algebra and Trigonometry 10th Edition

$\frac{x-1}{x}$, $x\ne0,1$
$f(x)=\frac{1}{1-x}$ Hence, f(f(x))=$\frac{1}{1-(\frac{1}{1-x})}=\frac{x-1}{x}$, x cannot be zero or 1 (domain calculation).