Question 3**+Identify the pivot columns in \(\begin{pmatrix}2&1&0&5\\0&3&-1&4\\0&0&0&1\end{pmatrix}\).
Question 4***Use back substitution to solve the echelon system represented by \(\begin{pmatrix}1&2&1&6\\0&1&-1&1\\0&0&2&4\end{pmatrix}\).
Question 5**+Row reduce the first column of \(\begin{pmatrix}2&1&5\\4&3&11\end{pmatrix}\) to get an echelon form.
Question 6**+Solve the echelon system \(\begin{pmatrix}1&-1&0\\0&2&6\end{pmatrix}\) in variables x and y.
Question 8***For echelon matrix \(\begin{pmatrix}1&2&0&3\\0&0&1&4\end{pmatrix}\), identify pivot variables and free variables using variables x, y, z.
Question 9**+Determine whether the echelon matrix \(\begin{pmatrix}1&2&3\\0&0&1\end{pmatrix}\) represents an inconsistent system in variables x and y.