Precalculus (10th Edition)

Published by Pearson
ISBN 10: 0-32197-907-9
ISBN 13: 978-0-32197-907-0

Appendix A - Review - A.7 Complex Numbers; Quadratic Equations in the Complex Number System - A.7 Assess Your Understanding - Page A60: 31

Answer

$-\dfrac{1}{2}+\dfrac{\sqrt{3}}{2}i$

Work Step by Step

Use special formula $(a+b)^2=a^2+2ab+b^2$. We have $a=\frac{1}{2}$ and $b=\frac{\sqrt{3}}{2}i $ $\left ( \dfrac{1}{2}+\dfrac{\sqrt{3}}{2}i \right )^2=\left ( \dfrac{1}{2}\right )^2+2\left(\dfrac{1}{2}\right)\left(\dfrac{\sqrt{3}}{2}i\right)+\left ( \dfrac{\sqrt{3}}{2}i \right )^2$ Simplify. $=\dfrac{1}{4}+\dfrac{\sqrt{3}}{2}i+\dfrac{3}{4}i^2 $ Use $i^2=-1$. $=\dfrac{1}{4}+\dfrac{\sqrt{3}}{2}i-\dfrac{3}{4} $ Simplify. $=\dfrac{1-3}{4}+\dfrac{\sqrt{3}}{2}i $ $=\dfrac{-2}{4}+\dfrac{\sqrt{3}}{2}i $ $=-\dfrac{1}{2}+\dfrac{\sqrt{3}}{2}i $ Hence, the solution in the standard form is $-\dfrac{1}{2}+\dfrac{\sqrt{3}}{2}i$.
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