Question

How do you determine the `(x,y)` point given `f(x)=y`?

Answer 1

See below.

Explanation:

The answer is basically in the questions: you have one point `x`, and a rule of association, the function `f`, which tells you how you must associate an output value `y` for each input value `x`.

So, pick your `x`, do whatever computation `f` requires, and you have a value `y`. This is your `(x,y)` couple.