Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

Published by Pearson
ISBN 10: 0-32193-104-1
ISBN 13: 978-0-32193-104-7

Appendix A - Review - A.11 Complex Numbers - A.11 Assess Your Understanding - Page A94: 22

Answer

$-10$

Work Step by Step

Multiply each term of the first complex number by each term of the second, then combine like terms and use the fact that $i^2=-1$ to obtain: $$ (-3+i)(3+i)=-3(3+i)+i(3+i) \\=-3(3)+(-3)(i)+i(3)+i(i) \\=-9-3i+3i+i^2 \\=-9+(-1) \\=-10 $$
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