【Example 6】Two first-year high school students participate in a chess competition for second-year high school students. During the competition, every two players play one game, the winner gets 1 point, the loser gets 0 points, and if it's a draw, each gets point. It is known that the two first-year students scored a total of 8 points, and each second-year player scored the same and an integer number of points. How many second-year students participated in the competition?
Problem 830
Official solution
Let the number of participants from the second year be , so together with the first year, there are participants, hence the number of matches played is , and the total score of all participants is . Among these, 8 points were scored by the first-year students, and the remaining points were evenly distributed among the second-year students. Therefore, according to the problem, we have
which means
Thus, if is odd, then must be an integer, which implies or 1. However, contradicts the fact that the two first-year students scored a total of 8 points, so ; if is even, then must be an integer, which implies must be a reduced fraction with a denominator of 2, hence .