Answer
$-21 - 15i$
Work Step by Step
RECALL:
(1) $a(b-c) = ac - bc$
(2) $i^2=-1$
Use rule (1) above to obtain:
$=3i(7i) - 3i(5)
\\=21i^2 - 15i$
Use rule (2) above to obtain:
$=21(-1) - 15i
\\=-21 - 15i$
Intermediate Algebra for College Students (7th Edition)
by Blitzer, Robert F.
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: 35
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