Answer
See below
Work Step by Step
The augmented matrix for the given system is:
$A^\#= \begin{bmatrix}
1 & 2 & 1|4\\
0 &1&-1|1\\1&3&0|0
\end{bmatrix} \approx \begin{bmatrix}
1 & 2 & 1|4\\
0 &1&-1|1\\0&1&-1|0
\end{bmatrix} \approx \begin{bmatrix}
1 & 2 & 1|4\\
0 &1&-1|1\\0&0&0|-5
\end{bmatrix}$
Then:
$1.A_{13}(-1)\\2.A_{23}(-1)$
From the last row, we have:
$0x_1+0x_2+0x_3=-5$
Hence, the system has no solution.
As a result,there are no common points to all three planes.
