Question

y=√(x-4)
How can i tell if this is a function or not without graphing?

Answer 1

if for any x it's not producing 2 values in the range

Answer 2

If you can plug in any number for x and get ONLY ONE output for y, then it is a function.


Because this occurs with this equation, this means that this is a function. How do I know? Because the square root function is aptly named so because it is indeed a function. So the square root of any nonnegative number is some nonnegative number (and it's only ONE number)

Answer 3

* I should point out that "any number for x" means "any number in the domain"