Matrices and Determinants: JEE Main 2005 Mathematics question

If ${a_1},{a_2},{a_3},........,{a_n},.....$ are in G.P., then the determinant $\Delta = \left| {\matrix{ {\log {a_n}} & {\log {a_{n + 1}}} & {\log {a_{n + 2}}} \cr {\log {a_{n + 3}}} & {\log {a_{n + 4}}} & {\log {a_{n + 5}}} \cr {\log {a_{n + 6}}} & {\log {a_{n + 7}}} & {\log {a_{n + 8}}} \cr } } \right|$ is equal to :