#### Answer

$-8$

#### Work Step by Step

Recall the following rule: $\sqrt{x^{2}}=x$. Thus, we obtain:
$-\sqrt {64}=-\sqrt {8^{2}}=-8$

Published by
Cengage Learning

ISBN 10:
1285194055

ISBN 13:
978-1-28519-405-9

$-8$

Recall the following rule: $\sqrt{x^{2}}=x$. Thus, we obtain:
$-\sqrt {64}=-\sqrt {8^{2}}=-8$

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