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# Sets and Sequences

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2.) If " S " is the set of all "x" such that 0&#8804;x&#8804;1, what points, if any, are points of accumulation of both "S" and C(S)?
3.) Prove that any finite set is closed.
5.) Prove that, if "S" is open, each of its points is a point of accumulation of "S".

1.) Suppose "S" is a set having the number "M" as its least upper bound. If "M" is not a member of "S", show that it is a point of accumulation of "S". Give an example showing that, if "M" does belong to "S" it need not be a point of accumulation of "S".

1.) Suppose that {Xn} is a sequence which is bound and such that all the values X1, X2, X3 .......... are distinct. Assume that the set of these values has just one point of accumulation, denoted by "X". Prove that the sequence is convergent and that the limit is "X".
2.) Consider the sequence with terms 2, 1/2, 4/3, ¼, 6/5, 1/6,.......... Where Xn = ½ [1-(-1) n ] + (1/n). Find two convergent subsequences with different limits.