Please help me solve this word problem:
In a round-robin chess tournament, each player is paired with every other player once. The function shown below, models the number of chess games, "N", that must be played in a round-robin tournament with "t" chess players. In a round-robin chess tournament, 55 games were played. How many players entered the tournament?

N=t^2-t divided by 2.

Question

Please help me solve this word problem:
In a round-robin chess tournament, each player is paired with every other player once.  The function shown below, models the number of chess games, "N", that must be played in a round-robin tournament with "t" chess players. In a round-robin chess tournament, 55 games were played. How many players entered the tournament?

N=t^2-t divided by 2.

anonymous · Answer

solve 
$$55=\frac{t^2-t}{2}$$ for t

anonymous · Answer

$$t^2-t=110$$
$$t^2-t-110=0$$
$$(t-11)(t+10)=0$$


$$t=11$$

anonymous · Answer

ahh thank you! I couldn't figure out haw to properly factor it