OCTOBER 13 , 2009

Solving Systems of Equations

Objectives

Content ObjectivesReview the addition/elimination method.Learn the substitution method.Language ObjectivesEveryone participates, actively listening

and/or being called on.Demonstrate knowledge in writing

(homework).

Page 817 # 1

2x -y=1-2x+3y=5

Page 817 # 2

x +3y=122x-3y=6

Page 817 #3

4x +3y= -55x +3y= -8

Page 817 #4

2x+3y=15x+3y=16

Page 817 #5

x +y= 83x-2y=4

Page 817 #6

x –y=-22x+3y=21

Inconsistent systems

Inconsistent system are systems which have no solutions.

2x-3y=14x-6y=1

Dependent Systems

Dependent systems have an infinite number of solutions.

-15x+21y=-2715y-21y=27

The Substitution Method

1. If necessary, solve one of the original equations for one of the variables.

2. Substitute the expression obtained in step one into the other equation to write an equation with a single variable.

3. Solve the equation in step 2.4. Plug the value you found in step 3 into one

of the original equations.5. Check your answers.

Try it

y = 6 x − 11−2 x − 3 y = −7

Try it

−4 x + y = 6−5 x − y = 21