Question

If In= (-1/(5n),1/(5n)) where n≥1 is an integer and In represents an interval on the real number line, find U(n=1 to infinity) In and ∩(n=1 to infinity) In.

Answer 1

Answer: $\bigcap In = \{0\},$ $\bigcup In = (\frac {1}{5},-\frac {1}{5}).$