Why use f(x) notations
You may ask WHY use f(x) and g(x), etc. and not just use y = notations. Here's a verbal analogy to help.
Suppose we look at the Smith family:
Mr. Smith, Mr. Smith and Mr. Smith are all sitting in a restaurant. Can you tell the father from his sons just from the names I told you? No, this is like using y = for every rule.
Now, Mr. Dave "Pop" Smith, Mr. Don "Sonny" Smith, and Mr. Bill "Bubba" Smith are sitting in a restaurant. Can you guess the father now? Using their first names and nicknames is like using function notation to tell them apart.
How would I respond to that?