3.2 Substitution Method.notebook
September 12, 2016
Warm Up
1. Is (­4, 3) a solution for the following system?
7x + 2y = ­22
3x ­ 2y = 2
Solve by substitution.
2. x = 7 ­ y 3. 2x ­ y = 2
x ­ y = 9 y = 13 ­ 3x
Warm Up Day 2
2x + 2y = 4
4. y = ½ x
Substitution Ex
1
3.2 Substitution Method.notebook
September 12, 2016
5.
Substitution­No soln
6.
Substitution­Inf solns
2
3.2 Substitution Method.notebook
September 12, 2016
Worksheet: Section 3.2
Answers
1. infinite solutions 2. (3, 1)
3. no solution 4. (­6, 4)
5. (1, 2) 6. (13, 30)
7. infinite solutions 8. (0, 0)
9. no solution 10. (12, 3)
Homework Answers
USING ELIMINATION TO SOLVE LINEAR SYSTEMS
Use elimination to solve a system of equations when:
one of the variables differs only in the sign (same coefficient but opposite signs)
Must be in standard form.
Example:
(from Alg 1)
STEPS:
1. Add the equations together.
2. The variable with the opposite signs will be eliminated.
3. Solve for the remaining variable.
4. Substitute the value for the remaining variable into either of the original equations and solve.
5. Check the ordered pair in both of the original equations. If it checks in both , this ordered pair is the solution to the system.
Elimination (when to use)
3