Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 10 - Section 10.6 - Determinants and Cramer's Rule - 10.6 Exercises - Page 743: 49

Answer

$(1,3,2)$

Work Step by Step

Step 1. Based on the Cramer’s Rule, with the given equations, we can define the following determinants: $\begin{array}( \\|D|= \\ \\ \end{array} \begin{vmatrix}2 &3&-5\\1&1&-1\\0&2&1 \end{vmatrix}, \begin{array}( \\|D_x|= \\ \\ \end{array} \begin{vmatrix}1 &3&-5\\2&1&-1\\8&2&1 \end{vmatrix}, \begin{array}( \\|D_y|= \\ \\ \end{array} \begin{vmatrix}2 &1&-5\\1&2&-1\\0&8&1 \end{vmatrix}, \begin{array}( \\|D_z|= \\ \\ \end{array} \begin{vmatrix}2 &3&1\\1&1&2\\0&2&8 \end{vmatrix}$ Step 2. Evaluate the above determinants: $|D|=(2)(1+2)-(1)(3+10)=-7$ (column1 expansion), $|D_x|=(1)(1+2)-(2)(3+10)+(8)(-3+5)=-7$ (column1 expansion), $|D_y|=(2)(2+8)-(1)(1+40)=-21$ (column1 expansion), $|D_z|=(2)(8-4)-(1)(24-2)=-14$ (column1 expansion), Step 3. Find the solutions as: $x=\frac{|D_x|}{|D|}=1$, $y=\frac{|D_y|}{|D|}=3$, $z=\frac{|D_z|}{|D|}=2$
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