Prove that ##S## is a subspace of ##V##

In summary, the question is asking if the subset ##S## of real infinite sequences with a limit of zero is a subspace of the space ##V## of all real sequences. The person is unsure how to apply their knowledge of vector spaces and subspaces to solve the problem. They also ask why an infinite sequence cannot represent an infinite dimensional vector if a three-dimensional vector can be represented by a three-element sequence.
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peregrintkanin
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Let ##S## be the subset of real (infinite) sequences (##a_1,a_2,\ldots##) with ##\lim a_n=0## and let ##V## be the space of all real sequences. Is ##S## a subspace of ##V##?

Hello. I want to ask for help to start solving this problem. I don't understand how I can apply the theory I've studied about vector spaces and vector subspaces.
 
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What are the properties that must be fulfilled in order for ##S## to be a subspace?
 
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peregrintkanin said:
Let ##S## be the subset of real (infinite) sequences (##a_1,a_2,\ldots##) with ##\lim a_n=0## and let ##V## be the space of all real sequences. Is ##S## a subspace of ##V##?

Hello. I want to ask for help to start solving this problem. I don't understand how I can apply the theory I've studied about vector spaces and vector subspaces.
If ##(a_1, a_2, a_3)## represents a three-dimensional vector, then why can't an infinite sequence ##(a_1, a_2, a_3 \dots )## represent an infinite dimensional vector?
 

What is a subspace?

A subspace is a subset of a vector space that satisfies all of the properties of a vector space. This means that it must contain the zero vector, be closed under vector addition and scalar multiplication, and follow the same rules for vector operations as the larger vector space.

How do you prove that a set is a subspace?

To prove that a set ##S## is a subspace of a vector space ##V##, you must show that it satisfies all of the properties of a vector space. This includes showing that the zero vector is in ##S##, that any two vectors in ##S## added together are still in ##S##, and that any scalar multiple of a vector in ##S## is also in ##S##.

What is the difference between a subset and a subspace?

A subset is simply a collection of elements that are contained within a larger set. A subspace, on the other hand, is a subset that also satisfies all of the properties of a vector space. So while all subspaces are subsets, not all subsets are subspaces.

Can a subspace be empty?

Yes, a subspace can be empty. In order for a set to be a subspace, it must contain the zero vector. If a set does not contain any vectors, it cannot contain the zero vector and therefore cannot be a subspace.

Can a subspace contain only one vector?

Yes, a subspace can contain only one vector. As long as the vector satisfies all of the properties of a vector space, it can be considered a subspace. This is known as a one-dimensional subspace.

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