Choose the one alternative that best completes the statement or answers thequestion.
Express in terms of i.
-$\sqrt{-81}$
A) $\pm 9$
B) - $9 \mathrm{i}$
C) $9 \mathrm{i}$
D) $-\mathrm{i} \sqrt{9}$

Question

Quizplus · Accepted Answer

The square root of -81 can be expressed as $\sqrt{-81} = \sqrt{81} \cdot \sqrt{-1} = 9i$, where $i$ is the imaginary unit defined as $\sqrt{-1}$.

Choose the One Alternative That Best Completes the Statement or Answers