Okay, so I'm having some trouble with this topic. If a question asks you to show that a set is a subspace (or not a subspace), do you show the following:
The set is not empty
The set is closed under vector addition, i.e.
The set is closed under scalar multiplication, i.e.
1) Show that the set
is not a subspace of
Would I do the following:
Therefore, it does not contain the vector, hence not a subspace in