Elementary Linear Algebra 7th Edition

Published by Cengage Learning
ISBN 10: 1-13311-087-8
ISBN 13: 978-1-13311-087-3

Chapter 5 - Inner Product Spaces - 5.1 Length and Dot Product in Rn - 5.1 Exercises - Page 235: 32

Answer

(a) $\|u\|=2\sqrt{2}, \quad \|v\|={\sqrt{5}}$. (b) Unit vector in direction of $v$ is $\frac{v}{\|v\|}=\frac{\sqrt{5}}{5}\left(\sqrt{2},-1,-\sqrt{2}\right)$. (c) Unit vector in direction opposite to $u$ is $-\frac{u}{\|u\|}=-\frac{\sqrt{2}}{4}\left(-1,\sqrt{3},2\right)$. (d) ${u} \cdot {v} =-3\sqrt{2}-\sqrt{3}$. (e)${u} \cdot {u}=8$. (f) ${v} \cdot {v}=5$.

Work Step by Step

(a) $\|u\|=2\sqrt{2}, \quad \|v\|={\sqrt{5}}$. (b) Unit vector in direction of $v$ is $\frac{v}{\|v\|}=\frac{\sqrt{5}}{5}\left(\sqrt{2},-1,-\sqrt{2}\right)$. (c) Unit vector in direction opposite to $u$ is $-\frac{u}{\|u\|}=-\frac{\sqrt{2}}{4}\left(-1,\sqrt{3},2\right)$. (d) ${u} \cdot {v} =-3\sqrt{2}-\sqrt{3}$. (e)${u} \cdot {u}=8$. (f) ${v} \cdot {v}=5$.
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