- #1
amilapsn
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Let ## f(x)=\begin{cases}1 &if \ x=\frac{1}{n} \ where \ n\epsilon \mathbb{Z}^{+}\\
0 & \mbox{otherwise}\end{cases}##
(i) Show that ##c\neq 0## then ##\lim_{x \to c}f(x)=0##
(ii) Show that ##\lim_{x \to 0}f(x)## does not exist.
I attempted to answer the question:
I think we have to show that:
##c\neq 0 \Rightarrow \lim_{x \to c}f(x)=0##
We know that,
##c\neq 0 \Leftrightarrow |c|>0##
##\lim_{x \to c}f(x)=0## means: ##\forall \epsilon>0 \ \exists \delta \ s.t. \forall x\epsilon \mathbb{R}##
##0<|x-c|<\delta \Rightarrow |f(x)|<\epsilon##
But I don't understand how to develop the proof any further... I think the question should begin with the statement: ##c\neq 0##
Please help me.
I have thought something of proving the first part but it's seems impossible to prove the second part.
0 & \mbox{otherwise}\end{cases}##
(i) Show that ##c\neq 0## then ##\lim_{x \to c}f(x)=0##
(ii) Show that ##\lim_{x \to 0}f(x)## does not exist.
I attempted to answer the question:
I think we have to show that:
##c\neq 0 \Rightarrow \lim_{x \to c}f(x)=0##
We know that,
##c\neq 0 \Leftrightarrow |c|>0##
##\lim_{x \to c}f(x)=0## means: ##\forall \epsilon>0 \ \exists \delta \ s.t. \forall x\epsilon \mathbb{R}##
##0<|x-c|<\delta \Rightarrow |f(x)|<\epsilon##
But I don't understand how to develop the proof any further... I think the question should begin with the statement: ##c\neq 0##
Please help me.
I have thought something of proving the first part but it's seems impossible to prove the second part.
Last edited: