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In linear algebra, vectors <math>v_1, v_2... v_n</math> form a basis for <math>\mathbb R^m</math> when
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In linear algebra, vectors <math>v_1, v_2... v_n</math> form a basis for the subspace V when
  
*The vectors [[span]] <math>\mathbb R^m</math>. (in other words, the span of the vectors is <math>\mathbb R^m</math>)
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*The vectors [[span]] V. (in other words, the span of the vectors is V)
 
*The vectors are [[Linearly Independent|linearly independent]].
 
*The vectors are [[Linearly Independent|linearly independent]].
  
For a basis, it follows that n must be equal to m.
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If V is a subspace of <math>\mathbb R^m </math> it follows that n must be less than or equal to m.
  
(Note that there can be more than one set of vectors that form a basis for the same space.)
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Note that there can be more than one set of vectors that form a basis for the same space. In fact, there are an infinite number of bases (plural of basis) for a subspace provided the subspace is not just <math>\vec 0</math>.  However, all bases for a given subspace have the same number of vectors. This number of vectors is called the dimension of the subspace.
  
 
[[category:MA351]]
 
[[category:MA351]]

Revision as of 17:07, 4 March 2010

In linear algebra, vectors $ v_1, v_2... v_n $ form a basis for the subspace V when

If V is a subspace of $ \mathbb R^m $ it follows that n must be less than or equal to m.

Note that there can be more than one set of vectors that form a basis for the same space. In fact, there are an infinite number of bases (plural of basis) for a subspace provided the subspace is not just $ \vec 0 $. However, all bases for a given subspace have the same number of vectors. This number of vectors is called the dimension of the subspace.

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