9:26 PM
@MartinSleziak Yes, I must define that the set contains pair of coordinates. So, I need $(x,y)$ where $x=0$ and $y$ a real number. Thank you.
If I want the set of the curve $y=kx^n$ where $k$ and $n$ are positive constants I could write it as $\{(x,kx^n); x,y\mathbb{R}\}$, right?
I mean the set which contains elements with $y=kx^n$.