#### Answer

$-40$

#### Work Step by Step

Using $i^2=-1$, the given expression, $
5i\cdot8i
,$ simplifies to
\begin{array}{l}\require{cancel}
40i^2
\\\\=
40(-1)
\\\\=
-40
.\end{array}

Published by
Pearson

ISBN 10:
0-32184-874-8

ISBN 13:
978-0-32184-874-1

$-40$

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