#### Answer

$6k\sqrt 2$

#### Work Step by Step

$\sqrt (72k^{2})=\sqrt (36\times k^{2}\times2)=\sqrt 36\times\sqrt k^{2}\times\sqrt 2=6k\sqrt 2$
We know that $\sqrt 36=6$, because $6^{2}=36$.
We know that $\sqrt k^{2}=k$, because $(k)^{2}=k^{2}$.

Published by
Pearson

ISBN 10:
0321969359

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

$6k\sqrt 2$

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