Calculus/Series

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Question
I have no idea where to start with this problem.

Consider the sequence a_n = ((-1)^n)/(sqrt(n))

(a) List the first 10 terms of this sequence (starting with n = 1) and plot them as points on a graph.

(b) Find a number A such that |a_n|< (1/5)  for all n > A.

(c) What is the limit as n approaches infinity of a_n

Answer
(a) can't really be done, but here are the terms:
1   -1
2   0.707106781
3   -0.577350269
4   0.5
5   -0.447213595
6   0.40824829
7   -0.377964473
8   0.353553391
9   -0.333333333
10   0.316227766

(b) For the term |a_n| to be less than 1/5, since we have a squareroot involved,
that would mean n would have to be greater than 5^2, so n > 25 would work.

(c) The limit is 0 since there is an n term in the denominator.

Calculus

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