question_answer 88)

If a, b, c are in A.P., then the determinant  is :       (a) 0                                    (b) 1       (c) x                                    (d) 2x  

Answer:

Given a, b, c are in A.P.             Let       Operate             Operate             Expand along C1, we get             = ? [(2c ? 2a) ?2 (2b ? 2a)]       = ? [2c ? 2a ? 4b + 4a]                              [Using (1)]              (a) is true.