Determinant Formulas and Cofactors

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Taught by OCW
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Lesson Summary:

In this lesson, you will learn how to find the determinant of matrices using two formulas: the messy formula and the cofactor formula. The messy formula involves choosing a term from every row and column of an n by n matrix and adding or subtracting them with a plus or minus sign. The cofactor formula involves choosing a specific row or column and using the minors and cofactors to form the determinant. Through examples of 2 by 2, 3 by 3, and n by n matrices, you will gain a solid understanding of how to apply these formulas.

Lesson Description:

Determinant Formulas and Cofactors -- Lecture 19. Learn some determinant formulas and how to compute determinants of matrices. Also, learn how to use cofactors to compute determinants.

Gilbert Strang, 18.06 Linear Algebra, Spring 2005. (Massachusetts Institute of Technology: MIT OpenCourseWare), (Accessed November 22, 2008). License: Creative Commons BY-NC-SA.
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Questions answered by this video:
  • What is the formula for a determinant?
  • What is a cofactor?
  • What is det A?
  • What are tridiagonal matrices?
  • How do you use cofactors to find a determinant?
  • Staff Review

    • Currently 4.0/5 Stars.
    This video is a complete lecture on finding determinants and formulas for determinants using cofactors. Some of the formulas get very complex and messy. A must-watch for determinants computation.