Precalculus (10th Edition)

Published by Pearson
ISBN 10: 0-32197-907-9
ISBN 13: 978-0-32197-907-0

Chapter 11 - Systems of Equations and Inequalities - 11.3 Systems of Linear Equations: Determinants - 11.3 Assess Your Understanding - Page 742: 29

Answer

$(x,y) =\left(\frac{3}{2},1\right)$

Work Step by Step

The given system of equations is $\left\{\begin{matrix} 2x& +&3y&=&6\\ x& -&y & =&\frac{1}{2} \end{matrix}\right.$ Determinant $D$ consists of the $x$ and $y$ coefficients. $D=\begin{vmatrix} 2&3 \\ 1& -1 \end{vmatrix}=(2)(-1)-(1)(3)=-2-3=-5$ For determinant $D_x$ replace the $x−$ coefficients with the constants. $D_x=\begin{vmatrix} 6&3 \\ \frac{1}{2}& -1 \end{vmatrix}=(6)(-1)-(\frac{1}{2})(3)=-6-\frac{3}{2}=-\frac{15}{2}$ For determinant $D_y$ replace the $y−$ coefficients with the constants. $D_y=\begin{vmatrix} 2&6 \\ 1& \frac{1}{2} \end{vmatrix}=(2)(\frac{1}{2})-(1)(6)=1-6=-5$ By using Cramer's rule we have. $x=\dfrac{D_x}{D}=\dfrac{-\frac{15}{2}}{-5}=\dfrac{3}{2}$ and $y=\dfrac{D_y}{D}=\dfrac{-5}{-5}=1$ Hence, the solution set is $(x,y) =\left(\frac{3}{2},1\right)$.
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.