Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 9 - Section 9.1 - Vectors in Two Dimensions - 9.1 Exercises - Page 637: 31

Answer

$2\vec{u}=\langle4,14\rangle$ $-3\vec{v}=\langle-9,-3\rangle$ $\vec{u}+\vec{v}=\langle5,8\rangle$ $3\vec{u}-4\vec{v}=\langle-6,17\rangle$

Work Step by Step

$\vec{u}=\langle2,7\rangle,$ $\vec{v}=\langle3,1\rangle$ $2\vec{u}$ Multiply both components of the vector $\vec{u}$ by $2$: $2\vec{u}=2\langle2,7\rangle=\langle4,14\rangle$ $-3\vec{v}$ Multiply both components of the vector $\vec{v}$ by $-3$: $-3\vec{v}=-3\langle3,1\rangle=\langle-9,-3\rangle$ $\vec{u}+\vec{v}$ Add the corresponding components from both vectors together: $\vec{u}+\vec{v}=\langle2,7\rangle+\langle3,1\rangle=\langle2+3,7+1\rangle=\langle5,8\rangle$ $3\vec{u}-4\vec{v}$ Multiply the vector $\vec{u}$ by $3$ and the vector $\vec{v}$ by $-4$, then evaluate the operation: $3\vec{u}-4\vec{v}=3\langle2,7\rangle-4\langle3,1\rangle=\langle6,21\rangle+\langle-12,-4\rangle=...$ $...=\langle6-12,21-4\rangle=\langle-6,17\rangle$
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