Chp. 6.4 ­ Elimination w. Multiplication
April 08, 2013
Date:
Chapter: Chapter 6:4 ­­> Elimination with Multiplication
Objectives: Solve systems of equations by using elimination
with multiplication
Algebra I
1
Chp. 6.4 ­ Elimination w. Multiplication
April 08, 2013
Notes:
The table shows the number of cars at Scott's Auto Repair Shop for each type of service.
Item
Body
Repairs
3
Maintenance
4
Engine
2
2
The manager has allotted 1110 minutes for body work and 570 minutes for engine work. Create a system of equations to represent the table to find the average time for each service.
Steps to Solve by Elimination Using Multiplication
1) Multiply one or both equations by a number so that one variable is the same number but opposites of each other.
2) Add equations then solve.
3) Substitute the value found in Step 2 into either equations and solve for the other variable.
Algebra I
2
Chp. 6.4 ­ Elimination w. Multiplication
April 08, 2013
Examples:
Ex. 1 ­ Use elimination to solve the system of equations.
a) 6x ­ 2y = 10
3x ­ 7y = ­19
c) 5x + 6y = ­8
2x + 3y = ­5
e) 5x ­ 3y = 6
2x + 5y = ­10
g) 4x + 2y = 8
3x + 3y = 9
Algebra I
b) 9r + q = 13
3r + 2q = ­4
d) 2x + y = 23
3x + 2y = 37
f) 6a + 2b = 2
4a + 3b = 8
h) 4x + 3y = 8
3x ­ 5y = ­23
3
Chp. 6.4 ­ Elimination w. Multiplication
April 08, 2013
Homework:
p. 358 (#8­18 Evens, 19)
Algebra I
4