1. COLLEGE ALGEBRA 4.4. Systems via Elimination Day One

2. Do Now: Welcome Back! Let’s see what you remember! Solve via substitution! Pull out your notes if you have no recollection how to do this! -8x + y = -6 -9x + 3y = 4y + x = 5 4x – 6 + y = 0y = 3x + 2 -5x – 5y = -25

3. Systems of Equations: Methods to solve: 1. Substitution 2. Graphing 3. ELIMINATION (what we are learning for the next two days)

4. Example One:

5. Example Two:

6. Realize: You have to determine whether you are adding the numbers together or subtracting them The goal? To get rid of one of the variables!

7. Example Three:

8. Example Four:

9. Steps for Elimination 1. Add/Subtract one equation from the other 2. The result should be an equation with just ONE variable 3. Solve for that variable 4. Plug in the solution into one of the original equations to determine the other variable.

10. You Try!

11. Example Five:

12. **Realize** Sometimes you may need to multiply/divide in order to eliminate successfully.

13. Example Six:

14. Example Seven:

15. You Try!

16. Practice Problems Try some on your own/in small groups As always if you are confused don’t hesitate to ask me questions.

17. Exit Ticket:

18. Exit Ticket Solve by elimination: -6x + 6y = 6 -6x + 3y = -12