let-X-R-wth-the-usual-metric-prove-that-the-open-and-bounded-interval-A-1-2-is-an-open-set-in-R-

Question Number 134940 by Oyins last updated on 08/Mar/21

l e t X = R w t h t h e u s u a l m e t r i c . p r o v e t h a t t h e o p e n

a n d b o u n d e d i n t e r v a l A = (1, 2) i s a n o p e n s e t i n R .