that is the bolzano-weierstrass theorem.
but I can't proof this way.
assume unbounded set S in R^n. -> an infinite subset T of S cannot
have a limit point.
please answer this proof.
If your textbook presents a standard theorem, such as
Bolzano-Weierstrass Theorem, but does not offer the proof,
get a better textbook.
And your wording does not come close to what is known as
Bolzano-Weierstrass Theorem. Just for the fun of it, show your
version to someone around you who is familiar both with your
first language and with English, and have him/her translate it
back. Then compare it with what the theorem really says.
(English is not my first language, either, so I know how hard it
is in the beginning.)
Cheers, ZVK(Slavek).