Elementary Linear Algebra 7th Edition

Published by Cengage Learning
ISBN 10: 1-13311-087-8
ISBN 13: 978-1-13311-087-3

Chapter 2 - Matrices - Review Exercises - Page 98: 10

Answer

$$x_1=5 , \quad x_2=2 , \quad x_3=-6$$.

Work Step by Step

The system can written on the form $Ax=b$ as follows $$x_1\left[ \begin {array}{cc} {2} \\{2}\\{4} \end {array} \right]+x_2\left[ \begin {array}{cc} {3}\\ {-3} \\{-2}\end {array} \right]+x_3\left[ \begin {array}{cc} {1}\\ {-3} \\{3}\end {array} \right]=\left[ \begin {array}{cc} {10}\\ {22}\\{-2} \end {array} \right].$$ To solve system using Gaussian elimination, we form the augmented matrix as follows $$\left[ \begin {array}{cccc} 2&3&1&10\\ 2&-3&-3&22 \\ 4&-2&3&-2\end {array} \right] . $$ The reduced row echelon form is given by $$ \left[ \begin {array}{cccc} 1&0&0&5\\ 0&1&0&2 \\ 0&0&1&-6\end {array} \right] . $$ From which, we have $$x_1=5 , \quad x_2=2 , \quad x_3=-6$$.
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