Use Cramer's Rule to solve: (x + 7y=23 (6x+y=15

Calculus: Early Transcendentals
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ISBN:9781285741550
Author:James Stewart
Publisher:James Stewart
Chapter1: Functions And Models
Section: Chapter Questions
Problem 1RCC: (a) What is a function? What are its domain and range? (b) What is the graph of a function? (c) How...
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Use Cramer's Rule to Solve

**Problem 2: Solving Simultaneous Equations Using Cramer's Rule**

Use Cramer's Rule to solve the following system of linear equations:

\[ 
\begin{align*}
x + 7y &= 23 \\
6x + y &= 15
\end{align*}
\]

**Cramer's Rule Overview:**

Cramer's Rule is a mathematical theorem used to solve systems of linear equations with as many equations as unknowns, using determinants.

To use Cramer's Rule, follow these steps:

1. **Determine the Coefficient Matrix (A):**
   \[
   A = \begin{bmatrix} 
   1 & 7 \\ 
   6 & 1
   \end{bmatrix}
   \]

2. **Calculate the Determinant of A (\(|A|\)):**
   \[
   |A| = (1)(1) - (7)(6) = 1 - 42 = -41
   \]

3. **Determine the Matrices for \(x\) and \(y\):**
   
   For \(x\), replace the first column of A with the constants:
   \[
   A_x = \begin{bmatrix} 
   23 & 7 \\ 
   15 & 1
   \end{bmatrix}
   \]
   For \(y\), replace the second column of A with the constants:
   \[
   A_y = \begin{bmatrix} 
   1 & 23 \\ 
   6 & 15
   \end{bmatrix}
   \]

4. **Calculate the Determinant of \(A_x\) and \(A_y\):**
   \[
   |A_x| = (23)(1) - (7)(15) = 23 - 105 = -82
   \]
   \[
   |A_y| = (1)(15) - (23)(6) = 15 - 138 = -123
   \]

5. **Apply Cramer's Rule to find \(x\) and \(y\):**
   \[
   x = \frac{|A_x|}{|A|} = \frac{-82}{-41} = 2
   \]
   \[
   y = \frac{|A_y|}{|A|} = \frac{-123
Transcribed Image Text:**Problem 2: Solving Simultaneous Equations Using Cramer's Rule** Use Cramer's Rule to solve the following system of linear equations: \[ \begin{align*} x + 7y &= 23 \\ 6x + y &= 15 \end{align*} \] **Cramer's Rule Overview:** Cramer's Rule is a mathematical theorem used to solve systems of linear equations with as many equations as unknowns, using determinants. To use Cramer's Rule, follow these steps: 1. **Determine the Coefficient Matrix (A):** \[ A = \begin{bmatrix} 1 & 7 \\ 6 & 1 \end{bmatrix} \] 2. **Calculate the Determinant of A (\(|A|\)):** \[ |A| = (1)(1) - (7)(6) = 1 - 42 = -41 \] 3. **Determine the Matrices for \(x\) and \(y\):** For \(x\), replace the first column of A with the constants: \[ A_x = \begin{bmatrix} 23 & 7 \\ 15 & 1 \end{bmatrix} \] For \(y\), replace the second column of A with the constants: \[ A_y = \begin{bmatrix} 1 & 23 \\ 6 & 15 \end{bmatrix} \] 4. **Calculate the Determinant of \(A_x\) and \(A_y\):** \[ |A_x| = (23)(1) - (7)(15) = 23 - 105 = -82 \] \[ |A_y| = (1)(15) - (23)(6) = 15 - 138 = -123 \] 5. **Apply Cramer's Rule to find \(x\) and \(y\):** \[ x = \frac{|A_x|}{|A|} = \frac{-82}{-41} = 2 \] \[ y = \frac{|A_y|}{|A|} = \frac{-123
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