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 - 11.1 Exercises - Page 755: 19

Answer

a) $ \lt \frac{8}{3}, 6\gt$ b) $\lt 6, -15 \gt$ c) $\lt -2, -14 \gt$ d) $ \lt 18, -7\gt$

Work Step by Step

$u = \lt 4, 9\gt$ $v = \lt 2, - 5\gt$ a) $\frac{2}{3}u$ $= \frac{2}{3} \lt 4, 9\gt$ $ = \frac{2}{3}(4i + 9j)$ $= \frac{8i}{3} + \frac{18j}{3}$ $= \lt \frac{8}{3}, 6\gt$ b) $3v$ $= 3\lt 2, - 5\gt$ $= 3(2i - 5j)$ $= 6i - 15j$ $= \lt 6, -15 \gt$ c) $v - u$ $= \lt 2, - 5\gt - \lt 4, 9\gt$ $= (2i - 5j) - (4i + 9j)$ $= 2i - 5j - 4i - 9j$ $= -2i - 14j$ $= \lt -2, -14 \gt$ d) $2u + 5v$ $= 2 \lt 4, 9\gt + 5\lt 2, - 5\gt$ $= 2(4i + 9j) + 5(2i - 5j)$ $= 8i + 18j + 10i - 25j$ $= 18i - 7j$ $= \lt 18, -7\gt$
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