Trigonometry (10th Edition)

Published by Pearson
ISBN 10: 0321671775
ISBN 13: 978-0-32167-177-6

Appendix A - Equations and Inequalities - Page 417: 57

Answer

{$-\frac{5}{2},2$}

Work Step by Step

Step 1: $2x^{2}+x=10$ Step 2: Subtracting 10 from both sides, $2x^{2}+x-10=10-10$ Step 3: The equation therefore becomes $2x^{2}+x-10=0$ Step 4: Comparing $2x^{2}+x-10=0$ to the standard form of a quadratic equation $ax^{2}+bx+c=0$; $a=2$, $b=1$ and $c=-10$ Step 5: The quadratic formula is: $x=\frac{-b \pm \sqrt (b^{2}-4ac)}{2a}$ Step 6: Substituting the values of a,b and c in the formula: $x=\frac{-(1) \pm \sqrt ((1)^{2}-4(2)(-10))}{2(2)}$ Step 7: $x=\frac{-1 \pm \sqrt (1+80)}{4}$ Step 8: $x=\frac{-1 \pm \sqrt (81)}{4}$ Step 9: $x=\frac{-1 \pm 9}{4}$ Step 10: $x=\frac{-1+9}{4}$ or $x=\frac{-1-9}{4}$ Step 11: $x=\frac{8}{4}$ or $x=\frac{-10}{4}$ Step 12: $x=2$ or $x=\frac{-5}{2}$ Step 13: Therefore, the solution set is {$-\frac{5}{2},2$}.
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