Answer:
Domain is

You'll check the box labeled "x", the box labeled
and the box labeled "d". So you'll have 3 boxes checked.
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Step-by-step explanation:
We cannot have a negative number under the square root, and get some real number output. For example, the result of
isn't a real number.
That means we need to have the "x-d" under the square root to be 0 or larger.

The domain is
telling us that x = d is the smallest x value we can plug in
So that's why we check off the box labeled "x", the box labeled
and the box labeled "d" as shown below.