Chapter 4: Problem 2
Determine a condition on \(|x-4|\) that will assure that: (a) \(|\sqrt{x}-2|<\frac{1}{2}\), (b) \(|\sqrt{x}-2|<10^{-2}\).
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Chapter 4: Problem 2
Determine a condition on \(|x-4|\) that will assure that: (a) \(|\sqrt{x}-2|<\frac{1}{2}\), (b) \(|\sqrt{x}-2|<10^{-2}\).
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Give examples of functions \(f\) and \(g\) such that \(f\) and \(g\) do not have limits at a point \(c\), but such that both \(f+g\) and \(f g\) have limits at \(c\).
Let \(f, g\) be defined on \(A\) to \(\mathbb{R}\) and let \(c\) be a cluster point of \(A\). (a) Show that if both \(\lim _{x \rightarrow c} f\) and \(\lim _{x \rightarrow c}(f+g)\) cxist, then \(\lim _{x \rightarrow c} g\) exists. (b) If \(\lim _{x \rightarrow c} f\) and \(\lim _{x \rightarrow c} f g\) exist, does it follow that \(\lim _{x \rightarrow c} g\) exists?
Let \(I:=(0, a)\) where \(a>0\), and let \(g(x):=x^{2}\) for \(x \in I\). For any points \(x, c \in I\), show that \(\left|g(x)-c^{2}\right| \leq 2 a|x-c| .\) Use this inequality to prove that \(\lim _{x \rightarrow c} x^{2}=c^{2}\) for any \(c \in I\).
Suppose that \(\lim _{x \rightarrow c} f(x)=L\) where \(L>0\), and that \(\lim _{x \rightarrow c} g(x)=\infty\). Show that \(\lim _{x \rightarrow c} f(x) g(x)=\) \(\infty\). If \(L=0\), show by example that this conclusion may fail.
Let \(c\) be a cluster point of \(A \subseteq \mathbb{R}\) and let \(f: A \rightarrow \mathbb{R}\). Prove that \(\lim _{x \rightarrow c} f(x)=L\) if and only if \(\lim _{x \rightarrow c}|f(x)-L|=0\)
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