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Linear Algebra

Core ideas and methods for systems of equations, vector spaces, linear transformations, and matrix analysis.

For: Learners at different starting points, from those meeting vectors and matrices for the first time to those revisiting the subject for further study.

After this page you can: Choose a useful learning path and explain how a linear algebra method represents or solves a problem.

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Part of: Mathematics

About Linear Algebra

Linear algebra studies systems of linear equations and the properties of matrices. It also develops ideas such as vector spaces, bases, and eigenvalues, which help describe how matrices act on vectors. You can place the subject within mathematics and follow related paths to statistics, calculus, or geometry.

A useful way to study is to work examples, then revisit what the calculations mean: begin with systems and elimination, build the language of spaces and bases, and continue to transformations, projections, and eigenvalues. Choose a route based on your current goal; you do not need to master every topic before applying the ideas.

Start here

route

I’m new to linear algebra

Start with MIT’s independent-study course and follow its lectures, notes, and problems in sequence.

Start with: Linear Algebra

route

I’m returning to the subject

Use the resource index to find a focused topic, then try its problems and check your work.

Start with: Resource Index: Linear Algebra

Learn the foundations

1.Solve systems with matricesStart with Ax = b, elimination, and the role of the column space in determining when a solution exists.

Start with Ax = b, elimination, and the role of the column space in determining when a solution exists.

Nullspace

The set of inputs x that solve Ax = 0.

Try it

In your own words, state the condition on b that makes Ax = b solvable.

Ax = b is solvable exactly when b belongs to the column space of A.

2.Build the language of vector spacesStudy subspaces, independence, bases, and dimension to describe the structure behind collections of vectors.

Study subspaces, independence, bases, and dimension to describe the structure behind collections of vectors.

Basis

A set of vectors, as few as possible, whose combinations produce all vectors in the space.

Dimension

The number of vectors in a basis for a space.

Try it

Explain what a basis provides for a vector space.

A basis is a set of vectors whose combinations produce all vectors in the space, with no more vectors than needed.

3.Understand transformations and determinantsConnect matrix multiplication to linear transformations, and use determinants to characterize important properties of square matrices.

Connect matrix multiplication to linear transformations, and use determinants to characterize important properties of square matrices.

Determinant

A value useful for determining whether a matrix is singular and computing its inverse.

Try it

Describe what a matrix does when it multiplies an input vector.

It produces an output vector, and the resulting rule can be studied as a linear transformation.

4.Use orthogonality and least squaresUse projections to connect orthogonality with least-squares fitting and approximation.

Use projections to connect orthogonality with least-squares fitting and approximation.

Orthogonal projection

The projection of a vector onto a subspace along a direction perpendicular to that subspace.

Least squares

A method for fitting a line or curve to data that can be viewed as finding a vector’s projection.

Try it

According to the projection view of least squares, what geometric operation does the method use?

It finds the projection of a vector.

5.Study eigenvalues and eigenvectorsExplore how eigenvalues and eigenvectors describe the effect of multiplying a vector by a matrix.

Explore how eigenvalues and eigenvectors describe the effect of multiplying a vector by a matrix.

Eigenvector

A nonzero vector whose product with a matrix points in the same direction as the vector.

Try it

In the relation Ax = λx, what does it mean for x to be an eigenvector?

It means Ax points in the same direction as x; λ is the corresponding eigenvalue.

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Books

Glossary

Every free Linear Algebra course and book on RedLectern

Free Linear Algebra online courses

  1. A Vision of Linear AlgebraMIT RES.18-010 · Browse materials · Video
  2. Algebra IMIT 18.701 · Browse materials
  3. Algebra IIMIT 18.702 · Browse materials
  4. Calculus Revisited: Complex Variables, Differential Equations, and Linear AlgebraMIT RES.18-008 · Browse materials · Video
  5. Differential EquationsMIT 18.03 · Browse materials · Video
  6. Differential EquationsMIT 18.03SC · Browse materials · Video
  7. Differential EquationsMIT ES.1803 · Browse materials
  8. Engineering Math: Differential Equations and Linear AlgebraMIT 2.087 · Browse materials · Video
Show all 22 coursesShow fewer courses
  1. Honors Differential EquationsMIT 18.034 · Browse materials
  2. Introduction to Functional AnalysisMIT 18.102 · Browse materials
  3. Introduction to Functional AnalysisMIT 18.102 · Browse materials · Video
  4. Introduction to Representation TheoryMIT 18.712 · Browse materials
  5. Linear AlgebraMIT 18.06 · Browse materials · Video
  6. Linear AlgebraMIT 18.06SC · Browse materials · Video
  7. Linear AlgebraMIT 18.700 · Browse materials
  8. Linear Algebra 1 (English)TU Delft OpenCourseWare · Browse materials · Video
  9. Seminar in Algebra and Number Theory: Rational Points on Elliptic CurvesMIT 18.704 · Browse materials
  10. Special Topics in Mathematics with Applications: Linear Algebra and the Calculus of VariationsMIT 2.035 · Browse materials
  11. Topics in Geometry: Dirac GeometryMIT 18.969 · Browse materials
  12. Honors Differential EquationsMIT 18.034 · Open on OCW
  13. Linear AlgebraMIT 18.06SC+summer_2019 · Open on OCW
  14. Linear Algebra - Communications IntensiveMIT 18.06CI · Open on OCW
How these courses are chosen

Listed as Linear Algebra courses:

  • those whose title contains “Linear Algebra”, or
  • those tagged “Linear Algebra” as one of at most 2 topic tags, or as the first of 3.

Free Linear Algebra textbooks and books

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