Linear algebraLesson 1 of 2 in the course Vector spaces

Vector-Space Bases: Dimension, Coordinates, and Change of Basis

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

A basis is a compact set of vectors that can build every vector in a space without redundancy. This lesson develops the two defining properties of a basis and explains why they guarantee unique coordinates.

Let VV be a vector space over a field FF, such as the real numbers R\mathbb{R} or complex numbers C\mathbb{C}. A subset BB of VV is a basis when it is both linearly independent and spanning.

All flashcards

What is a basis of a vector space?
A linearly independent set that spans the vector space.
Why does a basis give unique coordinates?
Spanning ensures a representation exists; independence ensures no two representations differ.
What is a minimal spanning set?
A spanning set from which removing any vector destroys the spanning property.
What is a maximal linearly independent set?
An independent set to which no vector can be added while preserving independence.
Why is a basis usually ordered when coordinates are used?
The order pairs each coordinate position with a particular basis vector.

Quiz questions

  1. What does the dimension of a vector space measure?Answer: The number of elements in any basis of the space.
  2. In an nn-dimensional vector space, when is a set of exactly nn vectors a basis?Answer: Exactly when it is linearly independent, or equivalently, when it spans.
  3. Let the columns of AA be the new basis vectors expressed in old-basis coordinates. If YY and XX are the new and old coordinate columns, respectively, what relation holds?Answer: X=AYX=AY
  4. What distinguishes a Hamel basis from an analytic basis that permits convergent series?Answer: Hamel expansions use finitely many terms; analytic expansions may use convergent infinite series.
  5. What is true of modules over rings compared with vector spaces over fields?Answer: A module need not have a basis; a module that has one is called free.

Based on the Wikipedia article Basis (linear algebra), licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.

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