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: 47

Answer

$(4,2,-1)$

Work Step by Step

Step 1. Based on the Cramer’s Rule, with the given equations, we can define the following determinants: $\begin{array}( \\|D|= \\ \\ \end{array} \begin{vmatrix} 1 &-1&2\\3&0 &1\\-1&2 &0 \end{vmatrix}, \begin{array}( \\|D_x|= \\ \\ \end{array} \begin{vmatrix} 0&-1&2\\11&0 &1\\0&2 &0 \end{vmatrix}, \begin{array}( \\|D_y|= \\ \\ \end{array} \begin{vmatrix} 1 &0&2\\3&11 &1\\-1&0 &0 \end{vmatrix}, \begin{array}( \\|D_z|= \\ \\ \end{array} \begin{vmatrix} 1 &-1&0\\3&0 &11\\-1&2 &0 \end{vmatrix}$ Step 2. Evaluate the above determinants: $|D|=(1)(0-2)-(-1)(0+1)+(2)(6+0)=11$ (row1 expansion), $|D_x|=-(11)((0-4)=44$ (column1 expansion), $|D_y|=(-1)(0-22)=22$ (row3 expansion), $|D_z|=(1)(0-22)-(-1)(0+11)=-11$ (row1 expansion), Step 3. Find the solutions as: $x=\frac{|D_x|}{|D|}=4$, $y=\frac{|D_y|}{|D|}=2$, $z=\frac{|D_z|}{|D|}=-1$
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