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Let $f : \mathbb{R}\to \mathbb{R}$ be given.

Suppose that $\lim_{x\to 0} f(x) = L$ and $f(0) = L$ . Prove that $\lim_{x\to 0}(f \circ g)(x) = L$, where $g(x) = xD(x)$:

How do I approach this? Fairly new to Calc and I tried looking for examples for some time but I can't quite explain

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    What is $D(x)$?2017-01-02

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If it is the case that for all $|x|<\epsilon$, for some $\epsilon>0$, that

$$|D(x)|

Then by squeeze theorem you should be able to see that

$$-M|x|\le xD(x)\le M|x|$$

$$\lim_{x\to0}xD(x)=0$$

And we know that if $f(x)$ is continuous around $x=0$, then

$$\lim_{x\to0}f(g(x))=f(\lim_{x\to0}g(x))=f(0)=0$$

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    Great. I understand now. Thanks!2017-01-02
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    @Pashtidot :D Glad to help!2017-01-02