When working with 2 x 2 linear systems,
you are working with
lines.
Two lines can intersect in a point, can be parallel to
one another, or can be the same line.

When working with 3 x 3 linear systems,
you are working with planes.
Three planes can intersect in a point, can intersect in a line,
can not intersect at all, or can all be the same plane.
All of which are difficult to display on paper.

3pic1aaWhen there is one point common to all
three planes, there will be a solution (an
ordered triple) to the 3x3 system.

The goal to solving a 3 x 3 system of linear equations is to find a value for each of the variables that will satisfy all three of the equations, making each equation true.

LINEAR SYSTEMS: Generally refer to 2 x 2 or 3 x 3 linear systems.
A 2 x 2 linear system deals with two variables, such as x and y.
A 3 x 3 linear system deals with three variables, such as x, y and z.

2 x 2 System of Linear Equations

systems2
Solution: (x, y) = (2,-2)

3 x 3 System of Linear Equations
3x3system
Solution: (x, y, z) = (1, 3, -2)

We found, when solving 2 x 2 systems, that there are three "basic" methods of arriving at the solution: an algebraic solution by substitution, an algebraic solution by elimination, and a graphical solution.

In the following section, we will investigate only the substitution method and the elimination method for solving 3 x 3 linear systems. The graphical approach will be addressed in a future course.

 

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