Math Problem Statement

Use Cramer's Rule to solve (if possible) the system of linear equations: 4x1 - x2 + x3 = -12, 2x1 + 2x2 + 3x3 = 9, 5x1 - 2x2 + 6x3 = 8.

Solution

The image shows a system of three linear equations:

4x_1 - x_2 + x_3 &= -12, \\ 2x_1 + 2x_2 + 3x_3 &= 9, \\ 5x_1 - 2x_2 + 6x_3 &= 8. \end{aligned}$$ The question asks to solve this system using **Cramer's Rule**. Based on the final answer shown in the image $$\left( \frac{-35}{9}, \frac{11}{9}, \frac{42}{9} \right)$$, the result was marked incorrect. Let's check why this might be. ### Steps to solve using Cramer's Rule: 1. **Find the determinant of the coefficient matrix** ($$D$$): $$A = \begin{pmatrix} 4 & -1 & 1 \\ 2 & 2 & 3 \\ 5 & -2 & 6 \end{pmatrix}$$ 2. **Calculate determinants of modified matrices**: - $$D_{x_1}$$, $$D_{x_2}$$, and $$D_{x_3}$$ by replacing the respective column in the matrix with the constants $$[-12, 9, 8]$$. 3. **Solve for** $$x_1$$, $$x_2$$, and $$x_3$$ using: $$x_1 = \frac{D_{x_1}}{D}, \quad x_2 = \frac{D_{x_2}}{D}, \quad x_3 = \frac{D_{x_3}}{D}.$$ Let me calculate this step by step to see what the correct solution should be.The determinant of the coefficient matrix $$A$$ is approximately $$55$$. Using Cramer's Rule, the solutions to the system of equations are: $$x_1 = -4, \quad x_2 = 1, \quad x_3 = 5.$$ It seems that the solution provided in the image $$\left( \frac{-35}{9}, \frac{11}{9}, \frac{42}{9} \right)$$ is incorrect, and the correct values for $$x_1, x_2, x_3$$ are $$-4$$, $$1$$, and $$5$$, respectively. Would you like more details or have any questions about this? Here are five questions related to this problem: 1. How is Cramer's Rule applied in 3x3 systems? 2. What happens if the determinant $$D$$ of the coefficient matrix is zero? 3. How do you calculate the determinant of a 3x3 matrix? 4. How is Cramer's Rule different from other methods like Gaussian elimination? 5. Can Cramer's Rule be applied to larger systems, such as 4x4 matrices? **Tip:** When using Cramer's Rule, always check the determinant of the coefficient matrix first. If it's zero, the system either has no solution or infinitely many solutions.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Linear Algebra
Systems of Linear Equations
Cramer's Rule
Matrix Determinants

Formulas

Determinant of 3x3 matrix: |A| = a(ei − fh) − b(di − fg) + c(dh − eg)
Cramer's Rule for x1: x1 = D_x1 / D
Cramer's Rule for x2: x2 = D_x2 / D
Cramer's Rule for x3: x3 = D_x3 / D

Theorems

Cramer's Rule
Determinant Theorem for Systems of Linear Equations

Suitable Grade Level

Undergraduate Linear Algebra