(A|\text{Ap})=\left(
\begin{array}{ccccc}
 1 & 7 & 6 & -1 & 7 \\
 1 & 4 & 2 & -1 & 1 \\
 2 & 3 & 2 & 2 & 2 \\
 3 & 1 & 3 & 7 & 6 \\
 2 & 2 & 3 & 4 & p
\end{array}
\right)
\begin{array}{c}
 I(-1)+\text{II} \\
 I(-2)+\text{III} \\
 I(-3)+\text{IV} \\
 I(-2)+V
\end{array}
\sim \left(
\begin{array}{ccccc}
 1 & 7 & 6 & -1 & 7 \\
 0 & -3 & -4 & 0 & -6 \\
 0 & -11 & -10 & 4 & -12 \\
 0 & -20 & -15 & 10 & -15 \\
 0 & -12 & -9 & 6 & p-14
\end{array}
\right)\text{IV}/(-5)\sim