Hmm.........i am not sure.but here;s my solution.......

 

 

 

The given condition should be satisfied to all values of x and y.

 

As a short cut method, put

 

x=y

 

or put

x=y=1

 

The determinant value will become "0" as all the 3 rows are identical.

 

hence,the answer is "0"

 

I am NOT sure of the answer,plz correct me if I am wrong.