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 - 11.2 The Quadratic Formula - 11.2 Exercise Set - Page 713: 37

Answer

$\left\{2, \dfrac{-1-\sqrt3i}{2}, \dfrac{-1+\sqrt3i}{2}\right\}$

Work Step by Step

The given equation is equivalent to $x^3-2^3=0$. Factor using the formula for difference of two cubes to obtain: \begin{align*} x^3-2^3&=0 \\ (x-2)(x^2+x+1)&=0 \end{align*} Use the Zero-Product Property by equating each factor to zero, then solve each equation to obtain: \begin{align*} x-2&=0 &\text{or}& &x^2+x+1=0\\\\ x&=2 &\text{or}& &x=\frac{-1\pm\sqrt{1^2-4(1)(1)}}{2(1)}\\\\ x&=2&\text{or}& &x=\frac{-1\pm\sqrt{1-4}}{2}\\\\ x&=2&\text{or}& &x=\frac{-1\pm\sqrt{-3}}{2}\\\\ x&=2&\text{or}& &x=\frac{-1\pm \sqrt{3}i}{2}\\\\ \end{align*} Thus, the solutions are: $\left\{2, \dfrac{-1\pm\sqrt3i}{2}\right\}$
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