Unit 1 Section 3­2.notebook
January 25, 2016
warm up 1/25/2016
algebraic substitution
6x + y = ­2
4x ­ 3y = 17
Step 1: Choose an equation, and solve for one of its variables. Step 2: Substitute your answer from step 1 into the equation you did not use. Step 3: Solve the equation. Step 4: Put your answer from step 3 into one of your original equations and solve. 6x + y = ­2
4x ­ 3y = 17
1
Unit 1 Section 3­2.notebook
January 25, 2016
you try...
2x + y = 4
4x ­ y = ­10
2
Unit 1 Section 3­2.notebook
January 25, 2016
one more time
2x + 4y = 12 x + 2y = 6
3
Unit 1 Section 3­2.notebook
January 25, 2016
you try...
2x + 4y = 8
­½x ­ y = ­10
4
Unit 1 Section 3­2.notebook
January 25, 2016
Conclusions
Remember this is only for solving
systems with TWO equations
One Solution
Infinitely Many
No Solution
5
Unit 1 Section 3­2.notebook
January 25, 2016
unit 1 3‐2 Continued
Elimination:
6x + y = ­2
4x ­ 3y = 17
Step 1: Make the coefficients of either x or y have the same number but opposite in sign.
*Do this by multiplying one or both equations by a number. Step 2: Add the equations together and solve. Step 3: Substitute your answer from step 2 into one of the equations and solve for the other variable. 6
Unit 1 Section 3­2.notebook
January 25, 2016
Use ELIMINATION to solve these systems.
x + 6y = 2
5x + 4y = 36
2x + 3y = ­1
­5x + 5y = 15
7
Unit 1 Section 3­2.notebook
January 25, 2016
homework
Pg. 145 #1­6, 8­12, 22­24 8