Intermediate Algebra for College Students (7th Edition)

Published by Pearson
ISBN 10: 0-13417-894-7
ISBN 13: 978-0-13417-894-3

Chapter 3 - Section 3.4 - Matrix Solutions to Linear Systems - Exercise Set - Page 229: 21

Answer

No solution or $\varnothing$.

Work Step by Step

The given system of equations is $4x-2y=5$ $-2x+y=6$ The augmented matrix is $\Rightarrow \left[\begin{array}{cc|c} 4 & -2 & 5\\ -2 & 1 & 6 \end{array}\right]$ Perform $R_1\rightarrow \frac{R_1}{4}$. $\Rightarrow \left[\begin{array}{cc|c} 4/4 & -2/4 & 5/4 \\ -2 & 1 & 6 \end{array}\right]$ Simplify. $\Rightarrow \left[\begin{array}{cc|c} 1 & -1/2& 5/4 \\ -2 & 1 & 6 \end{array}\right]$ Perform $R_2\rightarrow R_2+2\times R_1$. $\Rightarrow \left[\begin{array}{cc|c} 1 & -1/2 & 5/4\\ -2+2\times 1 & 1-2\times (1/2) & 6+2\times (5/4) \end{array}\right]$ Simplify. $\Rightarrow \left[\begin{array}{cc|c} 1 & -1/2 & 5/4\\ 0 & 0 & 17/2 \end{array}\right]$ Use back substitution to solve the linear system. $\Rightarrow (1)x+(-1/2)y=5/4$ and $\Rightarrow (0)x+(0)y=17/2$ In the second equation no values of $x$ and $y$ satisfy. Hence, the system is inconsistent and has no solution. The solution set is $\varnothing$.
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