College Algebra (6th Edition)

Published by Pearson
ISBN 10: 0-32178-228-3
ISBN 13: 978-0-32178-228-1

Chapter 1 - Equations and Inequalities - Exercise Set 1.5 - Page 161: 131

Answer

$7$ players

Work Step by Step

Plug the given number of games into the formula. Then multiply by the denominator on both sides and put all terms on one side. Then solve by finding two $x$-values that equal the third term when multiplied and add up to the coefficient of the second term. $N=\frac{x^2-x}{2}$ $21=\frac{x^2-x}{2}$ $42=x^2-x$ $x^2-x-42=0$ $(x+6)(x-7)=0$ $x=-6,7$ $x=7$ Only the positive value will matter since the question is asking for the number of players who were entered in the tournament.
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