Answer
$10$
Work Step by Step
$(3 - i)(3+i) = 9 +3i - 3i - i^2 = 9 - (-1) = 10$
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.