# Sequence of functions problem

Define $$f_n(x)= \begin{cases} 1-nx, &x\in [0,1/n],\\ 0, &x\in [1/n,1] \end{cases}$$

Then which of the following is correct:

1. $\lim_{n\to\infty}f_n(x)$ defines a continuous function on $[0,1]$.
2. $\{f_n\}$ converges uniformly on $[0,1]$.
3. $\lim_{n\to\infty}f_n(x)=0$ for all $x\in [0,1]$.
4. $\lim_{n\to\infty} f_n(x)$ exists for all $x\in[0,1]$.

Perhaps it would be helpful to first sketch the graphs of the first few $f_n$. –  David Mitra Dec 6 '12 at 12:26
I think only 4. is correct. This you can prove by choosing any $x \in [0,1]$. If $x=0$ then $f_n(0)=1$ for all $n$. If $x>0$ then for all $n > \frac{1}{x}$ f_n(x)=0\$. This is one of the standard examples on pointwise but non-uniform convergence, and is probably covered in most analysis courses...