Theorem
For an matrix , the followings are equivalent:
- is invertible;
- has only the trivial solution;
- ;
- is a product of elementary matrices;
- is consistent for every ;
- has exactly one solution for every ;
- ;
- The column vectors of are linearly independent;
- The row vectors of are linearly independent;
- The column vectors of span ;
- The row vectors of span ;
- The column vectors of is a basis for ;
- The row vectors of is a basis for ;
- ;
- .