Question

What is the domain of the function y= √ x+4?

Answer 1

Answer: Choice C

The x input of a square root function can be 0 or larger. If you take the square root of a negative number, then you'll get a complex number as a result. So we restrict the domain so that y is a real number.

We can say $x \ge 0$ or we can write what choice C shows to be more thorough, but they mean the same thing.

note: $0 \le x < \infty$ converts to the interval notation $[0, \infty)$