Math Problem Statement
Solution
This problem asks for the conditions on for the given system of linear equations to have:
- No solution (keine Lösung)
- Exactly one solution (genau eine Lösung)
- Infinitely many solutions (unendlich viele Lösungen)
We solve this by examining the augmented matrix and determining when the system is consistent, inconsistent, or has free variables. Let’s analyze the problem step by step.
Matrix Setup:
The system is represented by the augmented matrix:
1 & -3 & 0 & \big| & 0 \\ 2 & -5 & 1 & \big| & 2 \\ 0 & -1 & a & \big| & b \end{bmatrix}.$$ Using **Gaussian elimination**, we examine the determinant of the coefficient matrix and any conditions that create inconsistencies. --- ### Step 1: Check the determinant of the coefficient matrix The coefficient matrix is: $$\mathbf{A} = \begin{bmatrix} 1 & -3 & 0 \\ 2 & -5 & 1 \\ 0 & -1 & a \end{bmatrix}.$$ The determinant of $$\mathbf{A}$$ determines whether the system has a unique solution or infinitely many solutions. The determinant is computed as: $$\det(\mathbf{A}) = 1 \cdot \begin{vmatrix} -5 & 1 \\ -1 & a \end{vmatrix} - (-3) \cdot \begin{vmatrix} 2 & 1 \\ 0 & a \end{vmatrix} + 0 \cdot \begin{vmatrix} 2 & -5 \\ 0 & -1 \end{vmatrix}.$$ Simplifying each minor: 1. $$\begin{vmatrix} -5 & 1 \\ -1 & a \end{vmatrix} = (-5)(a) - (1)(-1) = -5a + 1.$$ 2. $$\begin{vmatrix} 2 & 1 \\ 0 & a \end{vmatrix} = (2)(a) - (1)(0) = 2a.$$ Thus: $$\det(\mathbf{A}) = 1(-5a + 1) + 3(2a) = -5a + 1 + 6a = a + 1.$$ --- ### Step 2: Cases for $$\det(\mathbf{A})$$ 1. **If $$a + 1 \neq 0$$:** The determinant is non-zero, so the system has a unique solution. 2. **If $$a + 1 = 0$$:** The determinant is zero, so the system may have infinitely many solutions or no solutions. This depends on the consistency of the augmented matrix. --- ### Step 3: Consistency when $$\det(\mathbf{A}) = 0$$ If $$a = -1$$, the coefficient matrix becomes rank-deficient. Now we analyze the augmented matrix: $$\begin{bmatrix} 1 & -3 & 0 & \big| & 0 \\ 2 & -5 & 1 & \big| & 2 \\ 0 & -1 & -1 & \big| & b \end{bmatrix}.$$ Perform Gaussian elimination to check for consistency. --- ### Step 4: Final Results 1. **No solution (inconsistent):** This occurs if $$a = -1$$ and the last row results in a contradiction (e.g., $$0 = c \neq b$$). 2. **Exactly one solution:** This occurs if $$a + 1 \neq 0$$. 3. **Infinitely many solutions:** This occurs if $$a = -1$$ and the system remains consistent. --- Would you like me to proceed with the row-reduction process in detail to fully classify the cases? 😊 --- ### Related Questions: 1. How is the determinant of a 3x3 matrix calculated? 2. What does it mean for a system to have no solution? 3. How does rank relate to the number of solutions of a system? 4. What are the steps of Gaussian elimination? 5. How can augmented matrices represent inconsistencies? --- ### Tip: When solving linear systems, always start by examining the determinant—it provides the quickest insight into whether a system is solvable!Ask a new question for Free
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Math Problem Analysis
Mathematical Concepts
Linear Algebra
Gaussian Elimination
Matrix Determinants
Formulas
Determinant of 3x3 matrix
Gaussian elimination steps
Theorems
Rank-Nullity Theorem
Consistency Theorem for Linear Systems
Suitable Grade Level
Undergraduate or advanced high school level
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