Algebra and Trigonometry 10th Edition

Published by Cengage Learning
ISBN 10: 9781337271172
ISBN 13: 978-1-33727-117-2

Chapter 8 - Review Exercises - Page 617: 75


$4-||u||=4-2\sqrt 5=2(2-\sqrt 5)$

Work Step by Step

$||u||=\sqrt {u·u}=\sqrt {⟨-4,2⟩⋅⟨-4,2⟩}=\sqrt {(-4)^2+2^2}=\sqrt {16+4}=\sqrt {20}=\sqrt {4(5)}=2\sqrt 5$ $4-||u||=4-2\sqrt 5=2(2-\sqrt 5)$
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