Precalculus (6th Edition) Blitzer

Published by Pearson
ISBN 10: 0-13446-914-3
ISBN 13: 978-0-13446-914-0

Chapter 8 - Section 8.5 - Determinants and Cramer's Rule - Exercise Set - Page 946: 56

Answer

The ${{D}_{x}}\text{ and }{{D}_{y}}$ are represented in terms of the coefficients and constants.

Work Step by Step

Given a linear system in two variables, $\begin{align} & {{a}_{1}}x+{{b}_{1}}y={{c}_{1}} \\ & {{a}_{2}}x+{{b}_{2}}y={{c}_{2}} \\ \end{align}$ Where $a_1$, $a_2$, $b_1$, $b_2$ are coefficients and $c_1$ and $c_2$ are constants. Then, $x=\frac{\left| \begin{matrix} {{c}_{1}} & {{b}_{1}} \\ {{c}_{2}} & {{b}_{2}} \\ \end{matrix} \right|}{\left| \begin{matrix} {{a}_{1}} & {{b}_{1}} \\ {{a}_{2}} & {{b}_{2}} \\ \end{matrix} \right|}$ And $y=\frac{\left| \begin{matrix} {{a}_{1}} & {{c}_{1}} \\ {{a}_{2}} & {{c}_{2}} \\ \end{matrix} \right|}{\left| \begin{matrix} {{a}_{1}} & {{b}_{1}} \\ {{a}_{2}} & {{b}_{2}} \\ \end{matrix} \right|}\text{ }$ Where, $\left| \begin{matrix} {{a}_{1}} & {{b}_{1}} \\ {{a}_{2}} & {{b}_{2}} \\ \end{matrix} \right|\ne 0$ Or $x=\frac{{{D}_{x}}}{D}\text{ and }y=\frac{{{D}_{y}}}{D}$ Where, $\begin{align} & {{D}_{x}}=\left| \begin{matrix} {{c}_{1}} & {{b}_{1}} \\ {{c}_{2}} & {{b}_{2}} \\ \end{matrix} \right| \\ & {{D}_{y}}=\left| \begin{matrix} {{a}_{1}} & {{c}_{1}} \\ {{a}_{2}} & {{c}_{2}} \\ \end{matrix} \right| \\ & \text{ and } \\ & {{D}_{{}}}=\left| \begin{matrix} {{a}_{1}} & {{b}_{1}} \\ {{a}_{2}} & {{b}_{2}} \\ \end{matrix} \right|\ne 0 \\ \end{align}$ So, ${{D}_{x}}\text{ and }{{D}_{y}}$ are represented in terms of the coefficients and constants.
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