Which intervals [a,b] in the set of reals have the property that (the set of rationals and [a,b]) is both open and closed in the set of rationals? And the property closed but not open?(adsbygoogle = window.adsbygoogle || []).push({});

**Physics Forums - The Fusion of Science and Community**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Closed and Open Sets Question

Loading...

Similar Threads for Closed Open Sets | Date |
---|---|

I Need closed form for a Binomial series | Feb 27, 2017 |

I Intersection & union of closed and open sets? | Sep 7, 2016 |

Real Analysis(open nor closed sets) | Feb 20, 2011 |

Whats the difference between a closed set vs a set thats NOT open? | Jan 29, 2010 |

Open and closed functions | Sep 14, 2005 |

**Physics Forums - The Fusion of Science and Community**