Question

cos(npi/2) why is it divergent?

Answer 1

from sigma 1 to infinity!

Answer 2

every time n is odd we get 0, but when n is even we get +/- 1. so this is the same as:

\[\sum_{n=1}^{\infty}(-1)^n\]

Answer 3

ok got it ! thanks :)

Answer 4

yep, so the term does not go to 0 as n goes to infinity

Answer 5

you're welcome