How do I solve this algebra word problem?

Question

The number of baseball games that must be scheduled in a league with n teams is given by the function

f(n)= (n² + n)/2, where each team plays every other team exactly once.  What are the zeros (solutions) of the equation?

 

The zeros seem to be 0 and -1 but I don't think that is correct.  You can't have a league with 0 or -1 teams.

Answer 1

The zeros are 0 and -1. The solutions to algebra are not necessary answers to the question.