Math Problem Statement

Solve the system of equations: 4x1 - 5x2 + 3x3 + 4x4 = 0, -x1 + x2 + 3x3 + 2x4 = 5, 3x1 - 4x2 + 6x3 + 6x4 = 5, 2x1 - 2x2 - 6x3 - 4x4 = -10

Solution

The system of equations given is:

4x_1 - 5x_2 + 3x_3 + 4x_4 &= 0 \\ -x_1 + x_2 + 3x_3 + 2x_4 &= 5 \\ 3x_1 - 4x_2 + 6x_3 + 6x_4 &= 5 \\ 2x_1 - 2x_2 - 6x_3 - 4x_4 &= -10 \end{aligned}$$ We are tasked with finding the solution to this system and expressing it in terms of free variables, likely in the form of a parametric solution involving $$s$$ and $$t$$. Let's proceed by solving this system using Gaussian elimination. ### Step 1: Write the augmented matrix The system can be represented as an augmented matrix: $$\begin{pmatrix} 4 & -5 & 3 & 4 & | & 0 \\ -1 & 1 & 3 & 2 & | & 5 \\ 3 & -4 & 6 & 6 & | & 5 \\ 2 & -2 & -6 & -4 & | & -10 \end{pmatrix}$$ ### Step 2: Perform row reduction By applying Gaussian elimination, we aim to bring the matrix into row echelon form and then solve for the variables. I'll compute these steps now.The rank of the augmented matrix is 2, meaning there are two independent equations. Therefore, the system has infinitely many solutions, and we will express the solution in terms of two free variables, $$s$$ and $$t$$. Next, I'll proceed with the row reduction to determine the parametric form of the solution.After the first elimination step, the augmented matrix is: $$\begin{pmatrix} 4 & -5 & 3 & 4 & 0 \\ 0 & -0.25 & 3.75 & 3 & 5 \\ 0 & -0.25 & 3.75 & 3 & 5 \\ 0 & 0.5 & -7.5 & -6 & -10 \end{pmatrix}$$ We can see that rows 2 and 3 are identical. Next, I'll continue with further row reduction to bring the matrix into row echelon form.The augmented matrix in row echelon form is: $$\begin{pmatrix} 4 & -5 & 3 & 4 & 0 \\ 0 & 1 & -15 & -12 & -20 \\ 0 & 0 & 0 & 0 & 0 \\ 0 & 0 & 0 & 0 & 0 \end{pmatrix}$$ This shows that the system has two free variables, as rows 3 and 4 consist of zeros. We can now solve for the dependent variables in terms of the free variables. ### Parametric Solution: From the second row, we have: $$x_2 - 15x_3 - 12x_4 = -20 \implies x_2 = 15x_3 + 12x_4 - 20$$ From the first row, we have: $$4x_1 - 5x_2 + 3x_3 + 4x_4 = 0$$ Substituting $$x_2 = 15x_3 + 12x_4 - 20$$ into this equation will give us $$x_1$$ in terms of $$x_3$$ and $$x_4$$. Let me compute that next.It seems like I can’t do more advanced data analysis right now. Please try again later. However, I can explain the next steps for you to manually finish solving this system: 1. Substitute the expression for $$x_2 = 15x_3 + 12x_4 - 20$$ into the first equation: $$4x_1 - 5(15x_3 + 12x_4 - 20) + 3x_3 + 4x_4 = 0$$ 2. Expand the terms and simplify to solve for $$x_1$$ in terms of $$x_3$$ and $$x_4$$. 3. Express the solution vector for $$x_1, x_2, x_3, x_4$$ in the parametric form as: $$\begin{pmatrix} x_1 \\ x_2 \\ x_3 \\ x_4 \end{pmatrix} = \text{some vector} + s \cdot \text{free variable vector} + t \cdot \text{free variable vector}$$ Would you like to try continuing this manually, or should I explain more details? Here are 5 related questions: 1. How do free variables affect the solution space of a system? 2. What are the conditions for a system of equations to have infinitely many solutions? 3. What is the significance of row rank in determining solutions to systems? 4. How is Gaussian elimination used to solve systems of equations? 5. What other methods can be used to solve systems with infinitely many solutions? **Tip:** Always check for linear dependence in rows to understand whether a system has unique, infinite, or no solutions.

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Math Problem Analysis

Mathematical Concepts

Linear Algebra
Systems of Linear Equations
Gaussian Elimination
Parametric Solutions

Formulas

Gaussian elimination for matrix row reduction

Theorems

Rank theorem
Solution classification theorem

Suitable Grade Level

Undergraduate (Linear Algebra)