1. OCTOBER 13, 2009 Solving Systems of Equations

2. Objectives Content Objectives Review the addition/elimination method. Learn the substitution method. Language Objectives Everyone participates, actively listening and/or being called on. Demonstrate knowledge in writing (homework).

3. Page 817 # 1 2x -y=1 -2x+3y=5

4. Page 817 # 2 x +3y=12 2x-3y=6

5. Page 817 #3 4x +3y= -5 5x +3y= -8

6. Page 817 #4 2x+3y=1 5x+3y=16

7. Page 817 #5 x +y= 8 3x-2y=4

8. Page 817 #6 x –y=-2 2x+3y=21

9. Inconsistent systems Inconsistent system are systems which have no solutions. 2x-3y=1 4x-6y=1

10. Dependent Systems Dependent systems have an infinite number of solutions. -15x+21y=-27 15y-21y=27

11. 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.

12. Try it y = 6 x − 11 −2 x − 3 y = −7

13. Try it −4 x + y = 6 −5 x − y = 21