Answer
$47i$
Work Step by Step
Make the square roots positive by moving the $i$ out of the radical. Then multiply and combine like terms.
$5\sqrt {-16}-3\sqrt {-81}$
$5i\sqrt {16}+3i\sqrt {81}$
$5i(4)+3i(9)$
$20i+27i$
$47i$
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.