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lim(x→1)(2x+1)=3をε-δ論法で示せ。
という問題の証明を教えてください。

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✨ Best Answer ✨

f(x)=2x+1とすると,
∀ε>0, ∃δ>0 s.t. ∀x∈ℝ [|x-1|<δ⇒|f(x)-3|<ε].
(∵|f(x)-3|=|2x-2|=2|x-1|より,δ=ε/2をとればよい)
ゆえに,lim[x→1]f(x)=3.

大学生

ありがとうございます!

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