Just, logged into thank you, Office Shredder, for your quick and helpful answer. Wich was very nice because it was precisely what I needed, to unblock my fixed ideas o a change of approach to face the problem and let me think or find an answer instead of just give me the result inmediately...
Homework Statement
Show that the range \mathcal{R}(T) of a bounded linear operator T: X \rightarrow Y is not necessarily closed.
Hint: Use the linear bounded operator T: l^{\infty} \rightarrow l^{\infty} defined by (\eta_{j}) = T x, \eta_{j} = \xi_{j}/j, x = (\xi_{j}).
Homework Equations...