1. Warm-up Twice the supplement of an angle is ten times the measure of the angle itself. Find the measure of both angles. Three times the complement of an angle is seven times the measure of the angle itself. Find the measure of both angles.

2. Solving Systems of Linear Equations

3. What is a System of Linear Equations? Wikipedia says it’s… A collection of linear equations that use the same variables

4. What does it mean to be a solution? It’s a coordinate pair that “works” in both equations Graphically: It’s where the lines intersect

5. 3 Different Methods Graphing Substitution Elimination/Linear Combination

6. Look at the Graph and Find the Solution to the system of equations

7. There are actually 3 cases Case 1 Case 2 Case 3 One Solution NO Solutions Infinite Solutions

8. Ok so now let’s look at it algebraically This is where the other two methods come in. Substitution Elimination/Linear Combination

9. Substitution Works best when one of your coefficients is 1 (ex: x + 3y = 7, x has a coefficient of 1 and y has one of 3.) First, get the variable with the coefficient of 1 alone (x = -3y + 7). Next, substitute the expression in for the variable you isolated into the 2 nd equation. Now you have an equation with one variable, so solve for that variable. Then, plug your answer into an original equation to find the other variable. So one of the equations (you choose which one) for one of the variables (you choose which one), and then plugging this back into the other equation, "substituting" for the chosen variable and solving for the other. Then you back-solve for the first variable.

10. Example

11. Elimination/Linear Combination First make one of the variables have opposite coefficients (if not already done) by multiplying. Then you will add the equations together which will cancel out one of the variables and allow you to solve for the other. Then you will plug it back into your equation and find the other variable.

12. Example

13. Try another…

14. How about some more!!

15. Flipped

16. Review

17. 3 Different Methods Graphing Substitution Elimination/Linear Combination

18. Look at the Graph and Find the Solution to the system of equations

19. There are actually 3 cases Case 1 Case 2 Case 3 One Solution NO Solutions Infinite Solutions

20. Substitution Works best when one of your coefficients is 1 (ex: x + 3y = 7, x has a coefficient of 1 and y has one of 3.) First, get the variable with the coefficient of 1 alone (x = -3y + 7). Next, substitute the expression in for the variable you isolated into the 2 nd equation. Now you have an equation with one variable, so solve for that variable. Then, plug your answer into an original equation to find the other variable. So one of the equations (you choose which one) for one of the variables (you choose which one), and then plugging this back into the other equation, "substituting" for the chosen variable and solving for the other. Then you back-solve for the first variable.

21. Example

22. Elimination/Linear Combination First make one of the variables have opposite coefficients (if not already done) by multiplying. Then you will add the equations together which will cancel out one of the variables and allow you to solve for the other. Then you will plug it back into your equation and find the other variable.

23. Example