Elementary Algebra

Published by Cengage Learning
ISBN 10: 1285194055
ISBN 13: 978-1-28519-405-9

Chapter 11 - Additional Topics - 11.4 - Complex Numbers - Problem Set 11.4: 47

Answer

$-26+15i$

Work Step by Step

We multiply each term of the first complex number with the second complex number and then simplify: $(-1-4i)(-2-7i)$ =$-1(-2-7i)-4i(-2-7i)$ =$2+7i+8i+28i^{2}$ =$2+15i+28(-1)$ [We substitute -1 in place of $i^{2}$ as $i^{2}=-1$] =$2-28+15i$ =$-26+15i$
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