Trigonometry (11th Edition) Clone

Published by Pearson
ISBN 10: 978-0-13-421743-7
ISBN 13: 978-0-13421-743-7

Appendix A - Equations and Inequalities - Page 420: 34



Work Step by Step

$2x^{2}-x-15=0$ $2x^{2}-6x+5x-15=0$ $2x(x-3)+5(x-3)=0$ $(x-3)(2x+5)=0$ $(x-3)=0$ or $(2x+5)=0$ $x=3$ or $x=-\frac{5}{2}$ Check: Substituting $x=3$ in the equation, $2(3)^{2}-3-15=0$ $18-3-15=0$ $18-18=0$ $0=0$ Substituting $x=-\frac{5}{2}$ in the equation, $2(-\frac{5}{2})^{2}-(-\frac{5}{2})-15=0$ $\frac{50}{4}+\frac{5}{2}-15=0$ $\frac{25}{2}+\frac{5}{2}-15=0$ $\frac{30}{2}-15=0$ $15-15=0$ $0=0$ Both values check and the solution set is {$-\frac{5}{2},3$}
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