#### Answer

-9

#### Work Step by Step

We know that $\sqrt 81=9$, because $9^{2}=9\times9=81$.
Therefore, we know that $-\sqrt 81=-(9)=-9$.

Published by
Pearson

ISBN 10:
0321969359

ISBN 13:
978-0-32196-935-4

-9

We know that $\sqrt 81=9$, because $9^{2}=9\times9=81$.
Therefore, we know that $-\sqrt 81=-(9)=-9$.

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