Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

Published by Pearson
ISBN 10: 0-32193-104-1
ISBN 13: 978-0-32193-104-7

Chapter 5 - Trigonometric Functions - Section 5.1 Angles and Their Measures - 5.1 Assess Your Understanding - Page 389: 135

Answer

$x=\dfrac{1}{5} ,-3 $

Work Step by Step

Put all terms on the left side: $5 x^{2}+2=5-14 x$ $5 x^{2}+2-5+14 x=0$ $5 x^{2}+14 x-3=0$ Solve using the Quadratic Formula $x=\dfrac{-b \pm \sqrt{b^{2}-4 a c}}{2a}$ with $a=5, b=14, \text{ and } c=-3$: $x=\dfrac{-14 \pm \sqrt{14^{2}-4(5)(-3)}}{2(5)}$ $x=\dfrac{-14 \pm \sqrt{196+60}}{10}$ $x=\dfrac{-14 \pm \sqrt{256}}{10}$ $x=\dfrac{-14 \pm 16}{10}$ $\begin{aligned} x&=\frac{-14+16}{10}(or) \frac{-14-16}{10} \\ x&=\frac{2}{10}\quad \text{or} \quad \frac{-30}{10} \\ x &=\frac{1}{5} \quad \text{or} \quad -3\end{aligned}$
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