$\"\"$

The function is $\"\"$ .

All possible values of $\"\"$ is the domain of the function.

Since the function $\"\"$ is a rational function, the denominator of the function should not be the zero.

$\"\"$

The domain of the $\"\"$ is the set of all real numbers $\"\"$ except $\"\"$ .

$\"\"$

The domain of the function $\"\"$ is all real numbers except 3; $\"\"$ .