Intermediate Algebra (6th Edition)

Published by Pearson
ISBN 10: 0321785045
ISBN 13: 978-0-32178-504-6

Appendix C - C - Exercise Set - Page 686: 32

Answer

$$x=-3,y=-2,z=5$$

Work Step by Step

We solve the given system of equations using Cramer's Rule. To do this, we turn the system into two matrices. We then create x, y, and z matrices by replacing the values in the original matrix with corresponding columns in the answer matrix. We then find determinants to solve. Doing this, we find: $$ M=\begin{pmatrix}2&-3&1\\ 1&1&1\\ 4&2&4\end{pmatrix} \\ M_2 = \begin{pmatrix}5\\ 0\\ 4\end{pmatrix}$$ So: $$ M_x=\begin{pmatrix}5&-3&1\\ 0&1&1\\ 4&2&4\end{pmatrix}\\ M_y=\begin{pmatrix}2&5&1\\ 1&0&1\\ 4&4&4\end{pmatrix} \\ M_z=\begin{pmatrix}2&-3&5\\ 1&1&0\\ 4&2&4\end{pmatrix} $$ Hence: $$ x=\frac{D_x}{D}=\frac{-6}{2} =-3 \\ y=\frac{D_y}{D}=\frac{-4}{2} =-2 \\ z=\frac{D_z}{D}=\frac{10}{2} =5 $$
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