Given:
The given function is:
To find:
The value of x that is in the domain.
Solution:
Domain is the set of input values.
We have,
We know that the square root is defined for non negative values. So,
Thus, the domain of the given function is all real number that are greater than or equal to 7.
In the given options 0, -3, 6 are less than 7 but 8 in option A is the only value that is greater than 7. So, is in the domain of the given function.
Therefore, the correct option is A.