Precalculus: Mathematics for Calculus, 7th Edition

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

Chapter 10 - Section 10.6 - Determinants and Cramer's Rule - 10.6 Exercises - Page 743: 50

Answer

$(-1,5,0)$

Work Step by Step

Step 1. Based on the Cramer’s Rule, with the given equations, we can define the following determinants: (use $x,y,z$ to represent $a,b,c$) $\begin{array}( \\|D|= \\ \\ \end{array} \begin{vmatrix}-2 &0&1\\1&2&-1\\3&5&2 \end{vmatrix}, \begin{array}( \\|D_x|= \\ \\ \end{array} \begin{vmatrix}2 &0&1\\9&2&-1\\22&5&2 \end{vmatrix}, \begin{array}( \\|D_y|= \\ \\ \end{array} \begin{vmatrix}-2 &2&1\\1&9&-1\\3&22&2 \end{vmatrix}, \begin{array}( \\|D_z|= \\ \\ \end{array} \begin{vmatrix}-2 &0&2\\1&2&9\\3&5&22 \end{vmatrix}$ Step 2. Evaluate the above determinants: $|D|=(-2)(4+5)-(0)+(1)(5-6)=-19$ (row1 expansion), $|D_x|=(2)(4+5)-(0)+(1)(45-44)=19$ (row1 expansion), $|D_y|=(-2)(18+22)-(2)(2+3)+(1)(22-27)=-95$ (row1 expansion), $|D_z|=(-2)(44-45)-(0)+(2)(5-6)=0$ (row1 expansion) Step 3. Find the solutions as: $x=\frac{|D_x|}{|D|}=-1$, $y=\frac{|D_y|}{|D|}=5$, $z=\frac{|D_z|}{|D|}=0$
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