# What is the domain of $f(x)=\large\frac{[x]+1}{[x]-1}$ where $[x]$ is greatest integer function

$\begin{array}{1 1} (1,20) \\ [1,2] \\ (-\infty,1)\cup [2,\infty) \\ (-\infty,1]\cup [2,\infty) \end{array}$

For f(x) to be defined $[x]-1\neq0$
$\Rightarrow\:[x]\neq 1$
$\Rightarrow\:x$ is any Real number and $x\notin [1,2)$
$x\in (-\infty,1)\cup [2,\infty)$