# Science:Math Exam Resources/Courses/MATH220/April 2011/Question 02

MATH220 April 2011
Other MATH220 Exams

### Question 02

For each of the following subsets of ${\displaystyle \mathbb {R} }$ write its supremum and infimum if they exist. If they do not exist write None. You do not need to prove your answers.

1. ${\displaystyle \left\{x\in \mathbb {R} {\text{ s.t. }}-1
2. ${\displaystyle \left\{x\in \mathbb {Q} {\text{ s.t. }}3\leq x^{2}\leq 7\right\},}$
3. ${\displaystyle \bigcap _{n=1}^{\infty }\left[2+{\frac {1}{n}},6-{\frac {2}{n}}\right],}$
4. ${\displaystyle \bigcup _{n=1}^{\infty }\left[{\frac {1}{n}},n\right].}$
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