Differential Equations and Linear Algebra (4th Edition)

Published by Pearson
ISBN 10: 0-32196-467-5
ISBN 13: 978-0-32196-467-0

Chapter 2 - Matrices and Systems of Linear Equations - 2.5 Gaussian Elimination - Problems - Page 166: 14

Answer

The system is inconsistent

Work Step by Step

The augmented matrix of the system is: $\begin{bmatrix} 3 &1 &5 |2\\ 1 &1 &-1| 1\\ 2& 1 & 2 |3 \end{bmatrix}$ with reduced row-echelon form: $\begin{bmatrix} 3 &1 &5 |2\\ 1 &1 &-1| 1\\ 2& 1 & 2 |3 \end{bmatrix} \approx^1 \begin{bmatrix} 1 &1 &-1| 1\\ 3 &1 &5 |2\\ 2& 1 & 2 |3 \end{bmatrix} \approx^2 \begin{bmatrix} 1 &1 &-1| 1\\ 0 &-2 &8 |-1\\ 0& -1 & 4|3 \end{bmatrix} \approx^3 \begin{bmatrix} 1 &1 &-1| 1\\ 0 &1 &-4 |\frac{1}{2}\\ 0& -1 & 4|3 \end{bmatrix} \approx^4 \begin{bmatrix} 1 &1 &-1| 1\\ 0 &1 &-4 |\frac{1}{2}\\ 0& 0 & 0|\frac{3}{2} \end{bmatrix}$ $1.P_{12}$ $2.A_{12}(-3), A_{13}(-2)$ $3.M_2(-\frac{1}{2})$ $4.A_{23}(1)$ This system of equations is inconsistent because $rank (A) \lt rank (A^\ne)$
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