Find the digital sum of the value of 1(2- ) (2- ^2 )+2(3- ) (3- ^2 )+ +9(10- ) (10- ^2 ), where is a complex...

Question

Find the digital sum of the value of 1(2- ) (2- ^2 )+2(3- ) (3- ^2 )+ +9(10- ) (10- ^2 ), where is a complex cube root of unity.

Accepted Answer

9

JEE Main Mathematics question