/sci/ - Science & Math

>>9280927
One of the exercises in this textbook has the solution listed as (-∞,3) U (3,∞), while my answer was (-∞,3) U [4,∞)
Would a professor mark that wrong? I obviously see why the former is the superior choice, but they both describe the same set, right? It's like in programming (int i = 0;i<=10;i++) vs (int i = 0;i<11;i++), right?