need help with this

13. Show that a sequence {on} converges to a if and only if each ball Br(a), with r > 0 contains all en's except for nitely many. 14. Suppose that ck 6 1R\" converges to a. Show that {ok a} converges to 0. Here (1;, a means the difference in each component, and 0 means (0,0,...,0) E R\