Answer
Domain: $(-\infty,6]$
Range: $[0, \infty)$
Work Step by Step
The expression under the square root must be greater than or equal to zero:
$6-x\geq0$
$x\leq6$
This can also be written as $(-\infty,6]$
The range of the library function $g(x)=\sqrt{x}$ is $[0, \infty)$
Likewise the range of $g(x)=\sqrt{6-x}$ is also $[0, \infty)$
