The system of linear equations in x1, x2, x3, where α, β ∈ R, has...
Understand the Problem
The question presents a system of linear equations involving three variables (x1, x2, x3) and parameters alpha and beta, and requests information regarding the conditions or solutions for this system.
Answer
A unique solution if $\beta \neq \alpha$; infinitely many solutions if $\beta = \alpha$ and $\alpha \neq 0$.
Answer for screen readers
The system has:
- A unique solution if $\beta \neq \alpha$.
- Infinitely many solutions if $\beta = \alpha$ and $\alpha \neq 0$.
Steps to Solve
- Write the Augmented Matrix
The system of linear equations can be represented in augmented matrix form as follows:
$$ \begin{pmatrix} 1 & 1 & 1 & | & 3 \ 0 & -1 & 2 & | & 1 \ \alpha & \beta & 0 & | & 0 \end{pmatrix} $$
- Row Reduction
Next, we apply row operations to simplify the matrix. Start by making zeros below the first leading 1 (the first column):
- Add $- \alpha R_1 + R_3$ to $R_3$.
This gives us a new third row:
$$ R_3 \rightarrow R_3 - \alpha R_1 $$
- Updated Augmented Matrix
Now the augmented matrix looks like this:
$$ \begin{pmatrix} 1 & 1 & 1 & | & 3 \ 0 & -1 & 2 & | & 1 \ 0 & \beta - \alpha & -\alpha & | & -3\alpha \end{pmatrix} $$
- Analyze Conditions for Solutions
For the system to have a unique solution, the last row must not lead to a contradiction. Set the condition for $\beta$ and $\alpha$:
- If $\beta - \alpha \neq 0$, the system has a unique solution.
- If $\beta - \alpha = 0$ leading to a zero row in the third leading position, we need to ensure $-3\alpha \neq 0$, which means $\alpha \neq 0$ for infinite solutions.
This gives us conditions for $\alpha$ and $\beta$.
- Final Conditions for $\alpha$ and $\beta$
The conditions derived are:
- For a unique solution: $\beta \neq \alpha$
- For infinite solutions: $\beta = \alpha$ and $\alpha \neq 0$.
The system has:
- A unique solution if $\beta \neq \alpha$.
- Infinitely many solutions if $\beta = \alpha$ and $\alpha \neq 0$.
More Information
This problem involves understanding how the parameters in a system of linear equations affect the solution set. The key is to analyze the row-echelon form of the augmented matrix to derive conditions for the parameters.
Tips
- Not performing row operations correctly can lead to incorrect conditions for the solution set. Care should be taken to ensure the integrity of each operation.
- Forgetting to check the determinant of the matrix formed by the coefficients can lead to incorrect conclusions.
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