Warm - Up

Are you smarter than a 4th grader???:

• There are three times as many dogs as birds

• There are 5 more cats than birds

• There are 24 cats

• How many dogs are there?

Alg2 Lesson 3-6Systems with 3 variables

Objectives:

1. Solve a system with 3 variables using elimination or substitution.

Graphs of Systems with 3 variables

Steps for Solving Systems of 3 Variables

• Use the first two equations and solve for one of the variables ( call new equation #4)

• Use the last two equations and solve for the same variable (call new equation #5)

• Use the two new equations (#4 and #5) and solve for one variable

• Substitute your known variable into equation #4 or #5 to solve for a second variable

• Substitute both known variables into one of the original equations to find final unknown variable

• Simple example:

2 3 6x y z 2 0y z

2z

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