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: 60

Answer

$85$

Work Step by Step

$\bf{\text{Solution Outline:}}$ To simplify the given expression, $ (6+7i)(6-7i) ,$ use the special product on multiplying the sum and difference of like terms. Then use $i^2=-1.$ $\bf{\text{Solution Details:}}$ Using the product of the sum and difference of like terms which is given by $(a+b)(a-b)=a^2-b^2,$ the expression above is equivalent \begin{array}{l}\require{cancel} (6)^2-(7i)^2 \\\\= 36-49i^2 .\end{array} Since $i^2=-1,$ the expression above is equivalent to \begin{array}{l}\require{cancel} 36-49(-1) \\\\= 36+49 \\\\= 85 .\end{array}
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