Answer:
All x-values larger than or equal to 5 ([tex]x\geq 5[/tex])
Step-by-step explanation:
Notice that the graph of
[tex]f(x)=-\sqrt{x}[/tex]
is defined for all real x-values larger than or equal to zero, since the square root is defined only for such values.
When we shift the graph to the right 5 units, the function becomes:
[tex]f(x)=-\sqrt{x-5}[/tex]
then the radicand x-5 must be larger than or equal to 0 in order to render real values. Then we have:
[tex]x-5\geq 0\\x\geq 5[/tex]
which means that now the Domain becomes the following set (in set builder notation):
[tex]Domain=\left \{ x\,|\,x\geq 5 \right \}[/tex]