Find all values of α such that series ∑ n = 1 ∞ ( 1...
Find all values of such that series
I used Maclaurin for sin and cos and got:
Put it together in one fraction seems to be a hard thing to do.
Answer & Explanation
You are on the right track. Note that
Hence, we see that
thus, when , the general term of your series , satisfies
and by the limit comparison test,