find the supremum and infimum of $E =\{x \in \mathbb{R} : -1/n \le x \le 1-1/n\}$

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![I am not sure how to start and what it the answer of this question please justify this answer of this question.]1

I am not sure how to start and what it the answer of this question please justify this answer of this question.

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In case this is homework, I'll get you started.

The set is $E = \bigcap\limits_{n=1}^\infty \left[-\frac {1}{n}, 1 - \frac {1}{n}\right]$. Try finding $E_k = \bigcap\limits_{n=1}^k \left[-\frac {1}{n}, 1 - \frac {1}{n}\right]$ for $k=1, 2, 3$, and then generalize the result to arbitrary values of $k$. Take the limit to get $E$.

You should find out that $E$ is an interval, which makes finding $\sup E$ and $\inf E$ easy.