- #1

ppy

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(i) if a[itex]\in[/itex]E and b[itex]\in[/itex]E[itex]^{c}[/itex] = ℝ\E and a < b then [a ,b] [itex]\cap[/itex]∂E IS NOT EQUAL TO ∅.

(ii) if a[itex]\in[/itex]E and b[itex]\in[/itex]E[itex]^{c}[/itex] = ℝ\E and a < b then (a ,b) [itex]\cap[/itex]∂E IS NOT EQUAL TO ∅.

I am really stuck I know that the frontier of a set is when a sequence in E and a sequence in E[itex]^{c}[/itex] converge to the same limit.