College Algebra 7th Edition

Published by Brooks Cole
ISBN 10: 1305115546
ISBN 13: 978-1-30511-554-5

Chapter 1, Equations and Graphs - Section 1.5 - Complex Numbers - 1.5 Exercises: 67

Answer

$-\frac{1}{2}\pm\frac{\sqrt{3}}{2}i$

Work Step by Step

$x^{2}+x+1=0$ We use the quadratic formula ($a=1, b=1, c=1$): $\displaystyle x=\frac{-(1)\pm\sqrt{(1)^{2}-4*1*1}}{2(1)}=\frac{-1\pm\sqrt{1-4}}{2}=\frac{-1\pm\sqrt{-3}}{2}=\frac{-1\pm \sqrt{3}i}{2}=-\frac{1}{2}\pm\frac{\sqrt{3}}{2}i$
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