The set can be expressed as:
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0 marksMathematicsReal analysisTopology of the real line: open, closed and compact setsModerateabout 2 min
DSE 2019 Question 48: Real analysis
Answer and worked solution
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Plain-text version
The set (0,∞) can be expressed as: (A) ∪ₙ₌₁^∞[aₙ,bₙ], where each aₙ and bₙ is a real number (B) ∪ₙ₌₁^∞(aₙ,bₙ), where each aₙ and bₙ is a real number (C) ∪ₙ₌₁^∞[aₙ,bₙ], where each aₙ and bₙ is a rational number (D) all of the above
Also written as: The set (0, inf) can be expressed as:
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 2019 paper. Solutions are TestStop's own. Not affiliated with or endorsed by any examination authority.