Let |A| = \(\begin{vmatrix}
1 & 1+p & 1+p+q \\[0.3em]
2 & 3+2p &1+3p+2q \\[0.3em]
3 & 6+3p & 1+6p+3q
\end{vmatrix}\)
Using the transformation R2 \(\longrightarrow\) R2 - 2R1,
R3\(\longrightarrow\) R3 - 3R1
Using R3 \(\longrightarrow\) R3 - 3R2
Expanding along column C1,we get
|A| = 1.