I now that the follow: In the metric space $(X,d)$ for every ball $T(x_0, r)$ goes $\overline {T(x_0,r)}\subset T[x,r]=\{x:d(x,x_0 \leq r)\}.$
But I didn`t know how to: Find an example of metric space which is not true equation.
Please help me. Thanks for your help and your attention. Thanks once again