Гост написа:[tex]\begin{array}{|l} \lambdax_{1 }+x_{2 }+x_{3} = 4 \\ x_{1 }+\mux_{2 }+x_{3 } = 3 \\ x_{1 }+2\mux_{2 }+x_{3 }=4 \end{array}[/tex]
Вероятно системата е така:
$$\begin{array}{|l} \lambda x_{1 }+x_{2 }+x_{3} = 4 \\ x_{1 }+\mu x_{2 }+x_{3 } = 3 \\ x_{1 }+2\mu x_{2 }+x_{3 }=4 \end{array}$$
Намираме детерминантите
$\Delta=
\begin{vmatrix}
\lambda& 1&1\\
1& \mu &1\\
1&2\mu&1
\end{vmatrix}
=\lambda.\mu+1+2\mu-\mu-\lambda.2\mu-1=\mu(1-\lambda)$
$\Delta_1=
\begin{vmatrix}
4& 1&1\\
3& \mu &1\\
4&2\mu&1
\end{vmatrix}
=4\mu+4+6\mu-4\mu-8\mu-3=1-2\mu$
$\Delta_2=
\begin{vmatrix}
\lambda& 4&1\\
1& 3 &1\\
1&4&1
\end{vmatrix}
=3\lambda+4+4-3-4\lambda-4=1-\lambda$
$\Delta_3=
\begin{vmatrix}
\lambda& 1&4\\
1& \mu &3\\
1&2\mu&4
\end{vmatrix}
=4\lambda.\mu+3+8\mu-4\mu-6\lambda.\mu-4=-2\lambda.\mu+4\mu-1$
$1.$ $\mu=0$ $\rightarrow$ $\Delta=0$, $\Delta_1\ne 0$, $\Delta_2\ne 0$, $\Delta_3\ne 0$ $\Rightarrow$ системата няма решение
$2.$ $\mu\ne0, \lambda=1$ $\rightarrow$ $\Delta=0$, $\Delta_1\ne 0$, $\Delta_2=0$, $\Delta_3\ne 0$ $\Rightarrow$ системата няма решение
$3.$ $\mu\ne0, \lambda\ne1$ $\rightarrow$ $\Delta\ne0$, $\Delta_1\ne 0$, $\Delta_2\ne 0$, $\Delta_3\ne 0$ $\Rightarrow$ системата има решение
$x_1=\frac{\Delta_1}{\Delta}=\cdots$, $x_2=\frac{\Delta_2}{\Delta}=\cdots$, $x_3=\frac{\Delta_3}{\Delta}=\cdots$