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 A61: 43

Answer

$-2+2i$

Work Step by Step

Use special formula $(a+b)^3=a^3+3a^2b+3ab^2+b^3$. We have $a=1$ and $b=i$. Thus, $\begin{align*} (1+i)^3&=1^3+3\cdot 1^2\cdot i+3\cdot 1\cdot i^2+i^3\\ &=1+3i+3i^2+i^3\end{align*}$ Use $i^3=-i$ and $i^2=-1$ then simplify. $=1+3i+3(-1)+(-i)$ $=1+3i-3-i$ $=-2+2i$ Hence, the solution in the standard form is $-2+2i$.
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