Answer:
The domain of a radical function is the set of all real numbers for which the function is defined. In this case, we have the function f(x) = √(x + 1) - 3.
For the function to be defined, the value inside the square root (√) must be non-negative, since the square root of a negative number is undefined in the real number system.
So, to determine the domain, we set the expression inside the square root greater than or equal to zero:
x + 1 ≥ 0
Solving for x:
x ≥ -1
Therefore, the domain of the given radical function is all real numbers greater than or equal to -1. In interval notation, the domain can be expressed as (-1, +∞).