Consider the system of equations : x + y + z = 0 `alpha x + beta y + gamma z = `0 `alpha^(2) x + beta^(2) y + gamma^(2) z = 0 ` then the system of equations has
A
a unique solution for all values of `alpha, beta , gamma `
B
infinite number of solutions if any two of `alpha, beta , gamma` are equal
C
a unique solution if `alpha, beta , gamma ` are distinct
D
more than one,but finite number of solutions depending on values of `alpha, beta, gamma `
Text Solution
AI Generated Solution
The correct Answer is:
To solve the given system of equations:
1. **Write down the equations:**
\[
\begin{align*}
1. & \quad x + y + z = 0 \\
2. & \quad \alpha x + \beta y + \gamma z = 0 \\
3. & \quad \alpha^2 x + \beta^2 y + \gamma^2 z = 0
\end{align*}
\]
2. **Form the coefficient matrix and set up the determinant:**
The coefficient matrix \( A \) can be represented as:
\[
A = \begin{bmatrix}
1 & 1 & 1 \\
\alpha & \beta & \gamma \\
\alpha^2 & \beta^2 & \gamma^2
\end{bmatrix}
\]
The determinant of this matrix, denoted as \( \Delta \), is:
\[
\Delta = \begin{vmatrix}
1 & 1 & 1 \\
\alpha & \beta & \gamma \\
\alpha^2 & \beta^2 & \gamma^2
\end{vmatrix}
\]
3. **Calculate the determinant using expansion:**
We can expand the determinant along the first row:
\[
\Delta = 1 \cdot \begin{vmatrix}
\beta & \gamma \\
\beta^2 & \gamma^2
\end{vmatrix} - 1 \cdot \begin{vmatrix}
\alpha & \gamma \\
\alpha^2 & \gamma^2
\end{vmatrix} + 1 \cdot \begin{vmatrix}
\alpha & \beta \\
\alpha^2 & \beta^2
\end{vmatrix}
\]
This results in:
\[
\Delta = (\beta \cdot \gamma^2 - \gamma \cdot \beta^2) - (\alpha \cdot \gamma^2 - \gamma \cdot \alpha^2) + (\alpha \cdot \beta^2 - \beta \cdot \alpha^2)
\]
Simplifying this gives:
\[
\Delta = \gamma^2(\beta - \alpha) + \alpha^2(\gamma - \beta) + \beta^2(\alpha - \gamma)
\]
4. **Analyze the determinant:**
- If \( \alpha, \beta, \gamma \) are distinct, then \( \Delta \neq 0 \) which implies a unique solution.
- If any two of \( \alpha, \beta, \gamma \) are equal, then \( \Delta = 0 \), which implies infinitely many solutions.
- If all three are equal, \( \Delta = 0 \) also leads to infinitely many solutions.
5. **Conclusion:**
- The system of equations has:
- A unique solution if \( \alpha, \beta, \gamma \) are distinct.
- Infinitely many solutions if any two (or all three) of \( \alpha, \beta, \gamma \) are equal.
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