Answer
$-\sqrt 57$
Work Step by Step
$\sqrt -3\times\sqrt -19=i\sqrt 3\times i\sqrt 19=i^{2}\sqrt (3\times19)=i^{2}\sqrt 57=-1\times\sqrt 57=-\sqrt 57$
We know that $\sqrt -1=i$, because $i^{2}=-1$.
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.