Calculus: Early Transcendentals (2nd Edition)

Published by Pearson
ISBN 10: 0321947347
ISBN 13: 978-0-32194-734-5

Chapter 11 - Vectors and Vector-Valued Functions - 11.4 Cross Products - 11.4 Exercises - Page 797: 34

Answer

\[\begin{align} & \mathbf{u}\times \mathbf{v}=-9\mathbf{i}+8.7\mathbf{j}+7\mathbf{k} \\ & \mathbf{v}\times \mathbf{u}=9\mathbf{i}-8.7\mathbf{j}-7\mathbf{k} \\ \end{align}\]

Work Step by Step

\[\begin{align} & \mathbf{u}=2\mathbf{i}-10\mathbf{j}+15\mathbf{k},\text{ }\mathbf{v}=0.5\mathbf{i}+\mathbf{j}-0.6\mathbf{k} \\ & \text{Calculate the cross product }\mathbf{u}\times \mathbf{v} \\ & \mathbf{u}\times \mathbf{v}=\left| \begin{matrix} \mathbf{i} & \mathbf{j} & \mathbf{k} \\ 2 & -10 & 15 \\ 0.5 & 1 & -0.6 \\ \end{matrix} \right| \\ & \mathbf{u}\times \mathbf{v}=\left| \begin{matrix} -10 & 15 \\ 1 & -0.6 \\ \end{matrix} \right|\mathbf{i}-\left| \begin{matrix} 2 & 15 \\ 0.5 & -0.6 \\ \end{matrix} \right|\mathbf{j}+\left| \begin{matrix} 2 & -10 \\ 0.5 & 1 \\ \end{matrix} \right|\mathbf{k} \\ & \mathbf{u}\times \mathbf{v}=\left( 6-15 \right)\mathbf{i}-\left( -1.2-7.5 \right)\mathbf{j}+\left( 2+5 \right)\mathbf{k} \\ & \mathbf{u}\times \mathbf{v}=-9\mathbf{i}+8.7\mathbf{j}+7\mathbf{k} \\ & \text{Calculate the cross product }\mathbf{v}\times \mathbf{u} \\ & \mathbf{v}\times \mathbf{u}=\left| \begin{matrix} \mathbf{i} & \mathbf{j} & \mathbf{k} \\ 0.5 & 1 & -0.6 \\ 2 & -10 & 15 \\ \end{matrix} \right| \\ & \mathbf{v}\times \mathbf{u}=\left| \begin{matrix} 1 & -0.6 \\ -10 & 15 \\ \end{matrix} \right|\mathbf{i}-\left| \begin{matrix} 0.5 & -0.6 \\ 2 & 15 \\ \end{matrix} \right|\mathbf{j}+\left| \begin{matrix} 0.5 & 1 \\ 2 & -10 \\ \end{matrix} \right|\mathbf{k} \\ & \mathbf{v}\times \mathbf{u}=\left( 15-6 \right)\mathbf{i}-\left( 7.5+1.2 \right)\mathbf{j}+\left( -5-2 \right)\mathbf{k} \\ & \mathbf{v}\times \mathbf{u}=9\mathbf{i}-8.7\mathbf{j}-7\mathbf{k} \\ \end{align}\]
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