Math Problem Statement

Solve the linear system 𝐴𝐱=𝐛Ax=b using Gaussian elimination.

𝐴=⎡⎣⎢⎢210301411⎤⎦⎥⎥𝐛=⎡⎣⎢⎢100⎤⎦⎥⎥.A=[234101011]b=[100].

Enter your answers below: The entries of 𝐱=[𝑥1𝑥2𝑥3]𝑇x=[x1x2x3]T are

𝑥1=x1= Answer 1 Question 4

𝑥2=x2= Answer 2 Question 4

𝑥3=x3= Answer 3 Question 4

Solution

We will solve the linear system Ax=bA \mathbf{x} = \mathbf{b} using Gaussian elimination.

Given system:

\mathbf{b} = \begin{bmatrix} 1 \\ 0 \\ 0 \end{bmatrix}$$ #### **Step 1: Augmented Matrix** $$[A | \mathbf{b}] = \begin{bmatrix} 2 & 3 & 4 & | 1 \\ 1 & 0 & 1 & | 0 \\ 0 & 1 & 1 & | 0 \end{bmatrix}$$ #### **Step 2: Forward Elimination** - Swap **row 1** and **row 2** to make the first pivot 1: $$\begin{bmatrix} 1 & 0 & 1 & | 0 \\ 2 & 3 & 4 & | 1 \\ 0 & 1 & 1 & | 0 \end{bmatrix}$$ - Eliminate first column below pivot: - Row 2 → Row 2 - 2 × Row 1: $$\begin{bmatrix} 1 & 0 & 1 & | 0 \\ 0 & 3 & 2 & | 1 \\ 0 & 1 & 1 & | 0 \end{bmatrix}$$ - Make second pivot 1 by dividing row 2 by 3: $$\begin{bmatrix} 1 & 0 & 1 & | 0 \\ 0 & 1 & \frac{2}{3} & | \frac{1}{3} \\ 0 & 1 & 1 & | 0 \end{bmatrix}$$ - Eliminate second column below pivot: - Row 3 → Row 3 - Row 2: $$\begin{bmatrix} 1 & 0 & 1 & | 0 \\ 0 & 1 & \frac{2}{3} & | \frac{1}{3} \\ 0 & 0 & \frac{1}{3} & | -\frac{1}{3} \end{bmatrix}$$ - Make third pivot 1 by multiplying row 3 by 3: $$\begin{bmatrix} 1 & 0 & 1 & | 0 \\ 0 & 1 & \frac{2}{3} & | \frac{1}{3} \\ 0 & 0 & 1 & | -1 \end{bmatrix}$$ #### **Step 3: Back Substitution** From the third row: $$x_3 = -1$$ From the second row: $$x_2 + \frac{2}{3}(-1) = \frac{1}{3}$$ $$x_2 - \frac{2}{3} = \frac{1}{3}$$ $$x_2 = 1$$ From the first row: $$x_1 + (-1) = 0$$ $$x_1 = 1$$ ### **Final Solution** $$\mathbf{x} = \begin{bmatrix} 1 \\ 1 \\ -1 \end{bmatrix}$$ **Answers:** - $$x_1 = 1$$ - $$x_2 = 1$$ - $$x_3 = -1$$ --- Do you want a more detailed explanation or any clarifications? Here are 5 related questions to expand your understanding: 1. How does Gaussian elimination handle inconsistent or dependent systems? 2. What is the difference between Gaussian and Gauss-Jordan elimination? 3. How can row swapping affect numerical stability in Gaussian elimination? 4. How does back substitution work in solving triangular systems? 5. What are the computational complexities of Gaussian elimination? **Tip:** Always check the determinant of $$A$$ to verify if a unique solution exists!

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Math Problem Analysis

Mathematical Concepts

Linear Algebra
Gaussian Elimination
Matrix Operations

Formulas

Gaussian elimination involves forward elimination to convert the matrix to row echelon form, followed by back substitution to find the solution.

Theorems

Gaussian Elimination Method

Suitable Grade Level

Undergraduate (Linear Algebra Course)