Answer
$20$
Work Step by Step
$4 \textbf i=4<1,0>=<4,0>$.
$5 \textbf i-9 \textbf j=5<1,0)-9<0,1>=<5,0>-<0,9>=<5,-9>$
$4 \textbf i\cdot (5 \textbf i-9 \textbf j)=<4,0>\cdot <5,-9>=4\cdot 5+0\cdot (-9)=20$
Trigonometry (11th Edition) Clone
by Lial, Margaret L.; Hornsby, John; Schneider, David I.; Daniels, Callie
Published by
Pearson
ISBN 10:
978-0-13-421743-7
ISBN 13:
978-0-13421-743-7
Chapter 7 - Applications of Trigonometry and Vectors - Section 7.5 - Applications of Vectors - 7.5 Exercises - Page 343: 51
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