1. Warmup
Solve the following system using SUBSTITUTION:

2. Questions over hw?

3. Solve Systems of Equations by Elimination

4. Solve by Graphing
Solution: (-1, 3)

5. Analyzing the Solution
Does the solution still work if you multiply one or both of the equations by a number like 2 or -2?
Solution: (-1, 3)

6. Steps for Elimination:
Arrange the equations with like terms in columns
Multiply, if necessary, to create opposite coefficients for one variable.
Add/Subtract the equations.
Substitute the value to solve for the other variable.
Write your answer as an ordered pair.
Check your answer.

7. EXAMPLE 1 (continued)
(-1, 3)

8. EXAMPLE 2
3x + 2y = 5 -3x + 4y = -3.5
(1.5, 0.25)

9. EXAMPLE 3
2x – 3y = -2 -4x + 5y = 2
(2, 2)

10. EXAMPLE 4
-8x + 2y = 7 -4x + y = –16
No Solution

11. EXAMPLE 5
2x + 3y = 1 3x – 2y = 8
(2, -1)

12. Classwork (1, 1) (-3, 4) (-1, 2) (-1, 2) (4, -2) (-4, -2) (2, -1)
Elimination
Use elimination to solve each system of equations.
2x + 3y = m + 3n = a - b = 2
x + 2y = m + 2n = a + 2b = 3
4x + 5y = x – 3y = x – 4y = -4
6x - 7y = x – y = x + 3y = -10
4x – y = a – 3b = x + 2y = 5
5x + 2y = a + 2b = x - 4y = 10
(1, 1)
(-3, 4)
(-1, 2)
(-1, 2)
(4, -2)
(-4, -2)
(2, -1)
(-1/2, 2)
(2.5, 0)

13. Homework
Practice Worksheet