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: 52

Answer

$(2,-1,3)$

Work Step by Step

Step 1. Based on the Cramer’s Rule, with the given equations, we can define the following determinants: $\begin{array}( \\|D|= \\ \\ \end{array} \begin{vmatrix}2 &-1&0\\5&0&3\\0&4&7 \end{vmatrix}, \begin{array}( \\|D_x|= \\ \\ \end{array} \begin{vmatrix}5 &-1&0\\19&0&3\\17&4&7 \end{vmatrix}, \begin{array}( \\|D_y|= \\ \\ \end{array} \begin{vmatrix}2 &5&0\\5&19&3\\0&17&7 \end{vmatrix}, \begin{array}( \\|D_z|= \\ \\ \end{array} \begin{vmatrix}2 &-1&5\\5&0&19\\0&4&17 \end{vmatrix}$ Step 2. Evaluate the above determinants: $|D|=(2)(0-12)-(5)(-7-0)=11$ (column1 expansion), $|D_x|=(5)(0-12)-(-1)(133-51)=22$ (row1 expansion), $|D_y|=(2)(133-51)-(5)(35-0)=-11$ (column1 expansion), $|D_z|=(2)(0-76)-(5)(-17-20)=33$ (column1 expansion), Step 3. Find the solutions as: $x=\frac{|D_x|}{|D|}=2$, $y=\frac{|D_y|}{|D|}=-1$, $z=\frac{|D_z|}{|D|}=3$
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