I have n roots of unity a1,a2,.....an...the wat is the value of the following??
(1-a1)(1-a2)....(1-an)...
A small correction/clarification/expansion:
where
.
But .
Therefore
etc.
By the way, is the product symbol (Multiplication - Wikipedia, the free encyclopedia), the multiplicative analogue of the summation symbol (Summation - Wikipedia, the free encyclopedia)