1. The problem statement, all variables and given/known data
Let R2 denote the usual (x, y)-plane. We can define a partition of R2 by using the
lines with slope 2. Describe the corresponding equivalence relation ∼ by giving the
conditions on the coordinates so that (x1, y1) ∼ (x2, y2).
2. Relevant equations
3. The attempt at a solution
I have we must have (y2-y1)/(x2-x1)=2