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: 26

Answer

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

Work Step by Step

The given system of equations is $\left\{\begin{matrix} 3x& +&3y&=&3\\ 4x& +&2y & =&\frac{8}{3} \end{matrix}\right.$ Determinant $D$ consists of the $x$ and $y$ coefficients. $D=\begin{vmatrix} 3&3 \\ 4& 2 \end{vmatrix}=(3)(2)-(4)(3)=6-12=-6$ For determinant $D_x$ replace the $x−$ coefficients with the constants. $D_x=\begin{vmatrix} 3&3 \\ \frac{8}{3}& 2 \end{vmatrix}=(3)(2)-(\frac{8}{3})(3)=6-8=-2$ For determinant $D_y$ replace the $y−$ coefficients with the constants. $D_y=\begin{vmatrix} 3&3 \\ 4& \frac{8}{3} \end{vmatrix}=(3)(\frac{8}{3})-(4)(3)=8-12=-4$ By using Cramer's rule we have. $x=\dfrac{D_x}{D}=\dfrac{-2}{-6}=\dfrac{1}{3}$ and $y=\dfrac{D_y}{D}=\dfrac{-4}{-6}=\dfrac{2}{3}$ Hence, the solution set is $(x,y) =\left(\frac{1}{3},\frac{2}{3}\right)$.
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.