1. The problem statement, all variables and given/known data I need to find an example of a set D[itex]\subseteq[/itex]R is compact but f-1(D) is not. 2. Relevant equations f-1(D) is the pre-image of f(D), not the inverse. 3. The attempt at a solution I'm having trouble visualizing a function that would work for this scenario. Any clues would be helpful.