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The system of equations $\begin{array}{l}\alpha x + y + z = \alpha - 1\\x + \alpha y + z = \alpha - 1\\x + y + \alpha z = \alpha - 1\end{array}$ has no solution, if $\alpha $ is
Not $ -2$
$1$
$-2$
Either $ -2$ or $ 1$
Solution
(c) For no solution or infinitely many solutions $\left| {\,\begin{array}{*{20}{c}}\alpha &1&1\\1&\alpha &1\\1&1&\alpha \end{array}\,} \right| = 0 \Rightarrow \alpha = 1,\alpha = – 2$.
But for $\alpha = 1$, clearly there are infinitely many solutions and when we put $\alpha = – 2$ in given system of equations and adding them together $L.H.S$ $ \ne $ $R.H.S$. i.e., No solution.
Similar Questions
Let $\alpha, \beta$ and $\gamma$ be real numbers. consider the following system of linear equations
$x+2 y+z=7$
$x+\alpha z=11$
$2 x-3 y+\beta z=\gamma$
Match each entry in List – $I$ to the correct entries in List-$II$
List – $I$ | List – $II$ |
($P$) If $\beta=\frac{1}{2}(7 \alpha-3)$ and $\gamma=28$, then the system has | ($1$) a unique solution |
($Q$) If $\beta=\frac{1}{2}(7 \alpha-3)$ and $\gamma \neq 28$, then the system has | ($2$) no solution |
($R$) If $\beta \neq \frac{1}{2}(7 \alpha-3)$ where $\alpha=1$ and $\gamma \neq 28$, then the system has |
($3$) infinitely many solutions |
($S$) If $\beta \neq \frac{1}{2}(7 \alpha-3)$ where $\alpha=1$ and $\gamma=28$, then the system has | ($4$) $x=11, y=-2$ and $z=0$ as a solution |
($5$) $x=-15, y=4$ and $z=0$ as a solution |
Then the system has