関連ワード:  how to prove a vector subspace    how to show a vector subspace    how to prove a linear subspace    how to prove a subspace linear algebra    how to prove something is a vector subspace    how to check vector subspace    how to show something is a vector subspace    how to prove if a vector is a subspace    how to show a vector space is a subspace    how to prove something is a subspace of a vector space