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: 48

Answer

$(1,-2,5)$

Work Step by Step

Step 1. Based on the Cramer’s Rule, with the given equations, we can define the following determinants: $\begin{array}( \\|D|= \\ \\ \end{array} \begin{vmatrix}5 &-3&1\\0&4&-6\\7&10&0 \end{vmatrix}, \begin{array}( \\|D_x|= \\ \\ \end{array} \begin{vmatrix}6 &-3&1\\22&4&-6\\-13&10&0 \end{vmatrix}, \begin{array}( \\|D_y|= \\ \\ \end{array} \begin{vmatrix}5 &6&1\\0&22&-6\\7&-13&0 \end{vmatrix}, \begin{array}( \\|D_z|= \\ \\ \end{array} \begin{vmatrix}5 &-3&6\\0&4&22\\7&10&-13 \end{vmatrix}$ Step 2. Evaluate the above determinants: $|D|=(5)(0+60)-0+(7)(18-4)=398$ (column1 expansion), $|D_x|=(1)(220+52)-(-6)(60-39)=398$(column3 expansion), $|D_y|=(5)(0-78)+(7)(-36-22)=-796$ (column1 expansion), $|D_z|=(5)(-52-220)+(7)(-66-24)=1990$ (column1 expansion) Step 3. Find the solutions as: $x=\frac{|D_x|}{|D|}=1$, $y=\frac{|D_y|}{|D|}=-2$, $z=\frac{|D_z|}{|D|}=5$
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