Intermediate Algebra (12th Edition)

Published by Pearson
ISBN 10: 0321969359
ISBN 13: 978-0-32196-935-4

Chapter 7 - Section 7.7 - Complex Numbers - 7.7 Exercises: 47

Answer

$-81$

Work Step by Step

$\bf{\text{Solution Outline:}}$ To simplify the given expression, $ (3i)(27i) ,$ multiply the numerical coefficients and multiply the $i$'s as if it were a literal coefficient. Then use $i^2=-1$. $\bf{\text{Solution Details:}}$ Multiplying the numerical coefficients and the $i$'s result to \begin{array}{l}\require{cancel} 81i^{1+1} \\\\= 81i^{2} .\end{array} Since $i^2=-1,$ the expression above is equivalent to \begin{array}{l}\require{cancel} 81(-1) \\\\= -81 .\end{array}
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