Answer:
It's called f of x
Explanation:
f (x) means function of x. For x any number, f (x) depends on the value of x. In each case x is a variable input. The output is f (x) which also varies depending on the x value used as input. f (x) is often referred to as y. Most likely, f (x) denotes the value of the function f when evaluated at the number x.