The expression under the square root must be non-negative
3x + 5 >= 0, or
3x >= -5, which implies
x >= .
Answer. The domain is the set { x >= }, or in the interval notation, [,).
What is it that you don't understand about this question? Are you unable to determine the range of values for which this function is defined, or do you not understand interval notation?
John
My calculator said it, I believe it, that settles it