IF A1,A2,A3,...,A(N-1) BE N-TH ROOTS OF THE UNITY THEN THE VALUE OF (A1/3-A1+A2/3-A2+A3/3-A3+...+A(N-1)/3-A(N-1))=

A)N/3^N-1

B)N-1/3^N-1

we know that  (x-1)(x-A1)(x-A2)...(x-A(N-1)) = x^n - 1

the denominator of LHS is 1 you can write 1 as A1.A2.A3.A4....A(N-1)

now you only have to do some arrangin take log on both sides,differentiate wrt x and put x=3.

u'll get the ans.

good luck