Question

So for this question it says, the graph of the function f(x)= radical of x+4 is shown. The domain of the function is
1) {x|x is greater than 0}
2) {x|x is greater or equal to 0}
3) {x|x is greater than -4}
4) {x|x is greater than or equal to -4}
I know that the answer is 4 but I really don't understand how do you find the domain of this function. Will someone explain??

Answer 1

√u is real only for positive u.

So, that means √(x+4) is real only for positive values of x+4:

x+4 >= 0
x >= -4