Answer: D: s∈ (-∞, 3]
Explanation:
When we have a function:
y = f(x)
The domain is the set of the possible values we can input in f(x).
In this case, we have:
y = √(3 - s)
Where our variable is s.
So we want to find the possible values of s we can input in that function.
Remember that if y is a real number, then we can not have a negative number inside the square root, because it will lead to an complex solution.
Then the argument of the square root needs to be equal to or larger than zero.
This means that:
3 - s ≥ 0
From this inequality, we can find the possible values of s, which will be the domain.
We need to isolate s.
3 ≥ s
This means that s needs to be smaller than or equal to 3.
Then the domain is:
D: s∈ (-∞, 3]