Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

Published by Pearson
ISBN 10: 0-32184-874-8
ISBN 13: 978-0-32184-874-1

Chapter 11 - Quadratic Functions and Equations - 11.1 Quadratic Equations - 11.1 Exercise Set - Page 707: 74

Answer

$$x=\frac{\sqrt{37}+5}{6},\:x=\frac{-\sqrt{37}+5}{6}$$

Work Step by Step

To find the x-intercepts, we set the equation equal to zero and then complete the square. Doing this, we find: $$ 3x^2-5x-1=0 \\ x^2-\frac{5x}{3}=\frac{1}{3}\\ x^2-\frac{5x}{3}+\left(-\frac{5}{6}\right)^2=\frac{1}{3}+\left(-\frac{5}{6}\right)^2\\ \left(x-\frac{5}{6}\right)^2=\frac{37}{36}\\ x=\frac{\sqrt{37}+5}{6},\:x=\frac{-\sqrt{37}+5}{6}$$
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