Posted by Bob on Sunday, September 19, 2010 at 8:21pm.
The sum from n=1 to infinity of cos(npi/3)/n!
Does this absolutely converge, conditionally converge, or diverge?

calculus  MathMate, Sunday, September 19, 2010 at 11:26pm
Group every 6 terms (1 cycle) together and consider as an aggregate term for a new series, ΣQn. Assume that all the terms are positive because of the n! in the denominator.
If you can prove that
Qn+1/Qn < 1, then
by the ratio test, the (new) series is absolutely convergent.
Can you take it from here?
Answer This Question
Related Questions
 Calculus 2  n=1 series to infinity (5^n)/n^3 does it absolutely converge, ...
 Calc 2  How would I do this one? n=1 to infinity n^n/4^1+3*n Does it absolutely...
 math  for what values of x does the series converge absolutely and for what ...
 Calculus  does the sum e^n / n! converge or diverge? n=1 > infinity
 Calculus  does the sum 3/(2^(n)1) converge or diverge? n=1>infinity
 CalculusPLZ HELP! =)  does the sum 3/(2^(n)1) converge or diverge? n=1>...
 Calculus  For the sequences below, find if they converge or diverge. If they ...
 calculus  Does the series from 0 to infinity of [1/square root of (n+4)] x cos(...
 Calculus  does the series 1/(n^2+n) converge or diverge? n=2 to n=infinity
 Calculus II  Does 3/(2^(n) +1) diverge or converge in an infinite sum?
More Related Questions