Let $f : [a,b] -> RR^n, n>=1$ and let $f(x)$ be continuos and $k$ times differentiable in $[a,b]$, show that also $f^((i))(x), 1<= i <=k$ is continuos in $[a,b]$ (with the notation $f^((i))(x)$ i mean that the function is derived $i$ times..)
Enjoy..