Show that the sequence $\displaystyle {f_n}$ defined by

$\displaystyle f_n(x) = \left\{

\begin{array}{c l}

n & x\geqslant n \\

0 & x<n

\end{array}

\right.

$

converges pointwise on $\displaystyle \mathbb{R}$ to the zero function $\displaystyle f(x)=0$

I know that I can pick any N such that when x < n and n > N i can get |f_n(x) - f(x)| = |f_n(x)| < epsilon. But I'm not sure how to show the convergence for x >orequalto n...