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 - 11.6 Calculus of Vector-Valued Functions - 11.6 Exercises - Page 816: 77

Answer

\[\left\langle {1 + 6{t^2},4{t^3}, - 2 - 3{t^2}} \right\rangle \]

Work Step by Step

\[\begin{gathered} {\text{Let }}{\mathbf{u}}\left( t \right) = \left\langle {1,t,{t^2}} \right\rangle {\text{ and }}{\mathbf{v}}\left( t \right) = \left\langle {{t^2}, - 2t,1} \right\rangle \hfill \\ \hfill \\ {\text{Calculate }}{\mathbf{u}}\left( t \right) \times {\mathbf{v}}\left( t \right) \hfill \\ {\mathbf{u}}\left( t \right) \times {\mathbf{v}}\left( t \right) = \left| {\begin{array}{*{20}{c}} {\mathbf{i}}&{\mathbf{j}}&{\mathbf{k}} \\ 1&t&{{t^2}} \\ {{t^2}}&{ - 2t}&1 \end{array}} \right| \hfill \\ {\mathbf{u}}\left( t \right) \times {\mathbf{v}}\left( t \right) = \left| {\begin{array}{*{20}{c}} t&{{t^2}} \\ { - 2t}&1 \end{array}} \right|{\mathbf{i}} - \left| {\begin{array}{*{20}{c}} 1&{{t^2}} \\ {{t^2}}&1 \end{array}} \right|{\mathbf{j}} + \left| {\begin{array}{*{20}{c}} 1&t \\ {{t^2}}&{ - 2t} \end{array}} \right|{\mathbf{k}} \hfill \\ {\mathbf{u}}\left( t \right) \times {\mathbf{v}}\left( t \right) = \left( {t + 2{t^3}} \right){\mathbf{i}} - \left( {1 - {t^4}} \right){\mathbf{j}} + \left( { - 2t - {t^3}} \right){\mathbf{k}} \hfill \\ \hfill \\ {\text{Calculate the derivative}} \hfill \\ \frac{d}{{dt}}\left[ {{\mathbf{u}}\left( t \right) \times {\mathbf{v}}\left( t \right)} \right] = \left( {1 + 6{t^2}} \right){\mathbf{i}} - \left( { - 4{t^3}} \right){\mathbf{j}} + \left( {} \right){\mathbf{k}} \hfill \\ \frac{d}{{dt}}\left[ {{\mathbf{u}}\left( t \right) \times {\mathbf{v}}\left( t \right)} \right] = \left( {1 + 6{t^2}} \right){\mathbf{i}} + 4{t^3}{\mathbf{j}} - \left( {2 + 3{t^2}} \right){\mathbf{k}} \hfill \\ or \hfill \\ \frac{d}{{dt}}\left[ {{\mathbf{u}}\left( t \right) \times {\mathbf{v}}\left( t \right)} \right] = \left\langle {1 + 6{t^2},4{t^3}, - 2 - 3{t^2}} \right\rangle \hfill \\ \end{gathered} \]
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