Let x∈R. Show the equivalence x=1⇔−ϵ<(x−1)<ϵ for all ε>0.
So the first thing I thought to do was to prove both sides (⇐ and ⇒) since this is an equivalence question.
i) To show ⇐:
Suppose x=1, we have to show −ϵ<(x−1)<ϵ for all ϵ>0.
$1
If x=1 then 1<(1+ϵ), ϵ>0
(x−1)<ϵ
(x−ϵ)<1
If x=1 then 1−ε<1
Therefore −ϵ<0, so ϵ>0.
Then i would go on to prove the ⇒side, but i'm not sure if i'm on the right line or not. Would really appreciate the help.
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