Is the Equation a Function?

Question

Determine if each equation given is a function. If it is or is not a function, explain the reason why. How do I know if an equation is a function or not?

(1) y = |x| + 4

(2) y = (1/x)

Answer 1

If the formula is a simple as y = something definitive for each value of x, as it is in these cases, it's a function.

The domain of the function may have some limitations; for example, 0 isn't in the domain of the second one. But it's a function.