We have a, b ∈ R \ Q, a < b.

A = {x ∈ Q: a < x < b}

Show that A is clopen(open and close) in Q

i have being trying to solve this problem in the last 2hours

i need some hints or examples

thank you in advance

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- Sep 28th 2009, 07:00 PMdonsmithMetric Space , Close and open
We have a, b ∈ R \ Q, a < b.

A = {x ∈ Q: a < x < b}

Show that A is clopen(open and close) in Q

i have being trying to solve this problem in the last 2hours

i need some hints or examples

thank you in advance - Sep 28th 2009, 07:22 PMJose27
- Sep 28th 2009, 08:18 PMdonsmith