Calculus 10th Edition

Published by Brooks Cole
ISBN 10: 1-28505-709-0
ISBN 13: 978-1-28505-709-5

Chapter 11 - Vectors and the Geometry of Space - Review Exercises - Page 811: 28

Answer

$${\bf{w}} = \frac{{12}}{5}{\bf{i}} + \frac{{16}}{5}{\bf{j}}$$

Work Step by Step

$$\eqalign{ & {\text{Let }}{\bf{u}} = 4{\bf{i}} + 2{\bf{j}},{\text{ }}{\bf{v}} = 3{\bf{i}} + 4{\bf{j}} \cr & {\text{Let }}{\bf{w}} = {\text{pro}}{{\text{j}}_{\bf{v}}}{\bf{u}} = \left( {\frac{{{\bf{u}} \cdot {\bf{v}}}}{{{{\left\| {\bf{v}} \right\|}^2}}}} \right){\bf{v}} \cr & {\bf{w}} = \left( {\frac{{\left( {4{\bf{i}} + 2{\bf{j}}} \right) \cdot \left( {3{\bf{i}} + 4{\bf{j}}} \right)}}{{{{\left\| {3{\bf{i}} + 4{\bf{j}}} \right\|}^2}}}} \right)\left( {3{\bf{i}} + 4{\bf{j}}} \right) \cr & {\bf{w}} = \left( {\frac{{12 + 8}}{{9 + 16}}} \right)\left( {3{\bf{i}} + 4{\bf{j}}} \right) \cr & {\bf{w}} = \frac{4}{5}\left( {3{\bf{i}} + 4{\bf{j}}} \right) \cr & {\bf{w}} = \frac{{12}}{5}{\bf{i}} + \frac{{16}}{5}{\bf{j}} \cr} $$
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