Intermediate Algebra for College Students (7th Edition)

Published by Pearson
ISBN 10: 0-13417-894-7
ISBN 13: 978-0-13417-894-3

Chapter 7 - Section 7.7 - Complex Numbers - Exercise Set: 8

Answer

$2i\sqrt{7}$

Work Step by Step

Factor the radicand so that one factor $-1$ to obtain: $=\sqrt{28(-1)} \\=\sqrt{4(7)(-1)} \\=\sqrt{2^2(7)(-1)}$ RECALL: (1) $\sqrt{abc} = \sqrt{a} \cdot \sqrt{b} \cdot \sqrt{c}$ (2) $\sqrt{-1} = i$ Use rule (1) above to obtain: $=\sqrt{2^2} \cdot \sqrt{7} \cdot \sqrt{-1} \\=2 \cdot \sqrt{7} \cdot \sqrt{-1} \\=2\sqrt{7} \cdot \sqrt{-1}$ Use rule (2) above to obtain: $=2\sqrt{7} \cdot i \\=2i\sqrt{7}$
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