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Course: Algebra II / Elementary Algebra
Topic: Linear Systems
Subtopic: 3x3 Systems of Equations

Overview

Now that we have the basic process of algebraically solving 2x2 systems down, we are ready to extend our knowledge to include larger linear systems (3x3, 4x4, etc.). Solving a 3x3 system algebraically still uses elimination/substitution methods, but the idea is to eliminate one variable/equation to transform the 3x3 system down to a 2x2 system, solve it, then back substitute to get all there variable answers.

The larger the systems get the more useful using technology to solve them becomes. I strongly recommend that you solve 4x4 and larger systems electronically. Because solving a 3x3 system algebraically is time-consuming, you may want to solve those electronically too (especially on a test), but be sure you know HOW to solve a 3x3 system algebraically.

Solving a linear systems electronically (on a handheld grapher or using a system solver program) requires using a command called RREF. How you do this will depend what technology you have available to you. See the supplemental resources below for suggestions.

Objectives

By the end of this topic you should know and be prepared to be tested on:

Terminology

Define: back substitution, matrix, row of a matrix, column of a matrix, size of a matrix (a.k.a. dimension, order), 3x3 system (and 4x4 system, etc.), augmented matrix, row reduced echelon form (RREF)

Text Notes
Text: Intro & Inter Algebra for CS 3ed by Blitzer, sect. 4.5

Supplementary Resources

Directions for solving a larger linear system electronically: