Linear Algebra and Its Applications, 4th Edition

Published by Brooks Cole
ISBN 10: 0030105676
ISBN 13: 978-0-03010-567-8

Chapter 2 - Section 2.2 - Solving Ax = 0 and Ax = b - Problem Set - Page 85: 4

Answer

u$\begin{bmatrix} -2 \\ 1 \\0\end{bmatrix}$ + $\begin{bmatrix} -3 \\ 0 \\2 \end{bmatrix}$; no solution

Work Step by Step

We know that x = $ x_{p}$ + $x_{n}$ In the first part, subtracting two times first row from second row gives $\begin{bmatrix} 1 & 2 & 2 \\ 0 & 0 & 1 \end{bmatrix}$ = $\begin{bmatrix} 0 \\ 0\end{bmatrix}$; which gives $x_{n}$ =u $\begin{bmatrix} -2 \\ 1 \\0\end{bmatrix}$ setting the free variable 'v' in the original two equations as 0 gives $x_{p}$ as $\begin{bmatrix} -3 \\ 0 \\2 \end{bmatrix}$. In second part, no solutions exist as row 2 is 2 times row 1, but 4 is not 2 times 1. Hence,geometrically this represents two parallel lines.
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