Trigonometry 7th Edition

Published by Cengage Learning
ISBN 10: 1111826854
ISBN 13: 978-1-11182-685-7

Chapter 7 - Section 7.5 - Vectors: An Algebraic Approach - 7.5 Problem Set - Page 405: 40

Answer

\begin{align*} U+V&=(0,8)\\ U-V&=(-8,0)\\ 2U-3V&=(-20,-4). \end{align*}

Work Step by Step

We have $U=\langle -4,4\rangle, V=\langle 4,4\rangle.$ First find $U+V$, \begin{align*} U+V=(-4,4)+(4,4)\\ &=(-4+4,4+4)\\ &=(0,8). \end{align*} Hence, $U+V=(0,8).$ Then find $U-V$, \begin{align*} U-V&=(-4,4)-(4,4)\\ &=(\left(-4\right)-4,4-4)\\ &=(-8,0). \end{align*} Hence, $U-V=(-8,0).$\\ In the end find, \begin{align*} 2U-3V&=2(-4,4)-3(4,4)\\ &=(-8,8)-(12,12)\\ &=\begin{pmatrix}\left(-8\right)-12,8-12\end{pmatrix}\\ &=(-20,-4). \end{align*}
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