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 - 11.1 Vectors in the Plane - 11.1 Exercises - Page 769: 65

Answer

$x=\left(\dfrac{4}{3},-\dfrac{11}{3}\right)$

Work Step by Step

We are given: $x=(a,b)$ $u=(2,-3)$ $v=(-4,1)$ $3x-4u=v$ Substitute the expressions of the vectors in the equation: $3(a,b)-4(2,-3)=(-4,1)$ $(3a,3b)-(8,-12)=(-4,1)$ $(3a-8,3b+12)=(-4,1)$ Determine $a,b$: $\begin{cases} 3a-8=-4\\ 3b+12=1 \end{cases}$ $\begin{cases} 3a=-4+8\\ 3b=1-12 \end{cases}$ $\begin{cases} 3a=4\\ 3b=-11 \end{cases}$ $a=\dfrac{4}{3}$ $b=-\dfrac{11}{3}$ The solution is: $x=\left(\dfrac{4}{3},-\dfrac{11}{3}\right)$
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