Intermediate Algebra for College Students (7th Edition)

Published by Pearson
ISBN 10: 0-13417-894-7
ISBN 13: 978-0-13417-894-3

Chapter 7 - Section 7.7 - Complex Numbers - Exercise Set - Page 570: 41

Answer

$-1-31i$

Work Step by Step

RECALL: (1) $(a-b)(c-d) \\= a(c-d) - b(c-d) \\=ac - ad - bc + bd$ (2) $i^2=-1$ Use rule (1) above to obtain: $=7(2-3i) - 5i(2-3i) \\=7(2) - 7(3i) - 5i(2) + 5i(3i) \\=14 - 21i - 10i +15i^2 \\=14 - 31i + 15i^2$ Use rule (2) above to obtain: $=14-31i+15(-1) \\=14-31i+(-15) \\=14-31i-15 \\=-1-31i$
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