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

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 $\left(x , y\right)$ couple.