More Lessons for Grade 9

Math Worksheets

Videos, worksheets, games and activities to help Algebra students learn how to find the determinant of a 3x3 matrix.

How to evaluate a determinant using row operations?

How to calculate the determinant using the diagonal method and cofactor method?

3x3 Determinant

Methods for computing a 3x3 determinant are important and are used when defining the cross product. Finding a 3x3 determinant is not as computationally heavy as finding the determinant of a larger square matrix. However, finding this determinant is more complicated than finding a 2x2 determinant. Using methods for simplifying determinants through row operations can make finding the 3x3 determinant much simpler.

Evaluating a Determinant Using Elementary Row Operations

Row Operation | Effect on Determinant |

Interchange two rows | Change the sign |

Multiply a row by a constant | Multiply by that constant |

Add a multiple of a row to another row | No change |

This video provides an example of how to calculate the determinant using the cofactor method.

Finding the Determinant of a 3 x 3 matrix.

This video shows the basic formula and compute the determinant of a specific matrix.

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