- #1

- 678

- 4

## Homework Statement

we know that a2 , a4 ,a6 (even number ) = 0 , but when a1 , a3 , a5 (odd numbers) , the answer of an alternate between positive and negative .... in the second circle , the author represent it with (-1)^(n+1) , i dont think this is correct , this is because when n=3 , an =

**-**2/ 3pi when n=3 , [ (-1) ^(3+1 ) ] = positive 1 , not negative 1 !!! can someone explain on this ?