Question

plz tell mistake. . . . . . ans is 4a²b²c²

Answer 1

Theres a mistake at 3rd step..where you apply

c2 -> c2 - c1
see entries of column 2 i.e, c2 after applying above Operation...
=> a - ( -a ) = a + a = 2a
=> -b - b = -2b
=> c - c = 0

Apply c3 -> c3 + 2c1 you will get following entries in Column 3 as
=> 2a + (-2a) = 2a - 2a =0
=> 0 + 2b = 2b
=> -2c + 2c = 0

Now you get two zeros in Ist row and expand the determinant...you will get your result...