Precalculus: Mathematics for Calculus, 7th Edition

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

Chapter 10 - Review - Test - Page 774: 12

Answer

$(5, -5, -4)$

Work Step by Step

Step 1. Define the following determinants: $|D|=\begin{vmatrix} 2&0&-1\\3&-1&5\\4&2&3\end{vmatrix}, |D_x|=\begin{vmatrix} 14&0&-1\\0&-1&5\\-2&2&3\end{vmatrix}, |D_y|=\begin{vmatrix} 2&14&-1\\3&0&5\\4&-2&3\end{vmatrix}, |D_z|=\begin{vmatrix} 2&0&14\\3&-1&0\\4&2&-2\end{vmatrix} $ Step 2. Evaluate the determinants (use row1 expansions, row3 expansion for $|D_y|$): $|D|=2(-3-10)-1(6+4)=-36, |D_x|=14(-3-10)-1(0-2)=-180, |D_y|=-3(42-2)-5(-4-56)=180, |D_z|=2(2-0)+14(6+4)=144$ Step 3. Find solution to the system using Cramer's Rule: $x=\frac{|D_x|}{|D|}=5, y=\frac{|D_y|}{|D|}=-5, z=\frac{|D_z|}{|D|}=-4$ which gives $(5, -5, -4)$
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