1. Solving Systems of Equations By Elimination
A-REI.3; A-REI.5; A-REI.6; A-REI.7

2. Table of Contents Pg
Title
LI/SC Flowchart
Elimination Method Notes

3. Learning Intention/Success Criteria
LI: We are learning how to solve a system of equations by elimination SC: I know how to -determine if a system of equations has many solutions -determine if a system of equations has no solutions -determine if a system of equations has one solution -solve systems of two linear equations algebraically using elimination method -solve equations for a variable -add integers -subtract integers

4. Example 1: Solve the system of equations using elimination method 2x + y = 10 5x – y = 18
_______________
7x = 28
____ 7
____ 7
x = 4
2x + y = 10 x = 4
Solution:
(4, 2)
2(4) + y = 10
8 + y = 10
_______________
- 8
- 8
y = 2

5. Example 2: Solve the system of equations using elimination method x + 5y = 33 -2x + 5y = -6
-1( )
_______________
x + 5y = 33 2x - 5y = 6 + + +
_______________
3x = 39
___ 3
___ 3
x = 13
x + 5y = 33 x = 13
Solution:
(13, 4)
13 + 5y = 33
5y = 20
y = 4

6. Example 3: Solve the system of equations using elimination method
8x – 3y = 3 3x – 2y = -5
-2 ( )
8x – 3y = 3 3x – 2y = -5
3 ( )
_______________
-16x + 6y = x – 6y = -15
_______________
-7x = -21
___ -7
___ -7
x = 3
8x - 3y = 3 x = 3
Solution:
8(3) - 3y = 3
(3, 7)
y = 3
- 3y = -21
y = 7