Lesson: Three-by-Three Determinants Mathematics

In this lesson, we will learn how to evaluate 3x3 determinants using the cofactors (Laplace expansion) or the Sarrus method.

Lesson Plan

Objectives

Students will be able to

  • define minors and cofactors in a matrix,
  • use the cofactors method (Laplace expansion) to evaluate a 3×3 determinant,
  • use the Sarrus method to evaluate a 3×3 determinant.

Prerequisites

Students should already be familiar with

  • 2×2 determinants.

Exclusions

Students will not cover

  • determinants of 4×4 and higher-dimensional matrices,
  • properties of determinants.

Lesson Video

Video Thumbnail
15:14

Lesson Explainer

Sample Question Videos

  • 02:10
  • 05:27
  • 06:14

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