Linear Algebra, subspaces and row reducing

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SUMMARY

The discussion clarifies that a basis for a subspace spanned by a set of vectors is indeed equivalent to the basis that forms the column space of the corresponding matrix. The dimension of this subspace matches the dimension of the column space. Row reducing the matrix is essential as it reveals the pivot columns, which indicate the linearly independent vectors, thereby identifying any redundant vectors in the set. The Rank-Nullity Theorem is also referenced as a critical concept that relates the pivots of a matrix to its rank.

PREREQUISITES
  • Understanding of linear algebra concepts, specifically subspaces and bases.
  • Familiarity with matrix operations, particularly row reduction techniques.
  • Knowledge of the Rank-Nullity Theorem and its implications.
  • Ability to identify pivot columns in a matrix.
NEXT STEPS
  • Study the Rank-Nullity Theorem in detail to understand its applications.
  • Practice row reducing matrices to identify pivot columns and redundant vectors.
  • Explore the relationship between column space and row space in linear algebra.
  • Learn about different methods for finding bases of subspaces in vector spaces.
USEFUL FOR

Students of linear algebra, educators teaching matrix theory, and anyone interested in understanding the foundational concepts of vector spaces and their dimensions.

flyingpig
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Homework Statement



This is just a conceptual question

Whenever you are asked for a basis for the subspace spanner by some set of vectors, is that the same as asking the basis that forms the column space of that matrix? Are the dimension for that subspace the same as the column space?

The other thing bothers me is that why is it that we have to put these vectors in a matrix and row reduce it to see the pivot columns, what is the magic in row reducing that tells us which vector is "redundant" in the set?
 
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If the basis of your subspace is contained within a matrix, then yes, it is the basis of the column space. In other words, it is the image of the matrix. And yes, the dimension of the image is the dimension of the subspace.

For your last question, have you looked to the Rank-Nullity Theorem? This should give you an answer to your question. Think about how the pivots of a matrix relate to the rank.
 

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