The set is identical to
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2 marksMathematicsReal analysisTopology of the real line: open, closed and compact setsModerateabout 3 min
DSE 2007 Question 44: Real analysis
Answer and worked solution
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Plain-text version
The set ⋂ₙ₌₁^∞(-1-n⁻¹, 1+n⁻¹) is identical to (A) (-1,1] (B) [-1,1) (C) (-1,1) (D) [-1,1]
Also written as: The set intersection_(n=1)^(inf)(-1-n^(-1), 1+n^(-1)) is identical to
Real analysis has come up 38 times in 5 exams since 2005.
What this question tests
This question is on Topology of the real line: open, closed and compact sets, part of Real analysis in Mathematics.
Which sets are open, closed or compact and how unions and intersections behave.
TestStop has 29 past-paper questions on this subtopic.
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Question from the DSE 2007 paper. Solutions are TestStop's own. Not affiliated with or endorsed by any examination authority.