Alg2 Chapter 3.notebook
September 07, 2016
[39] 3.2 Solving Systems Algebraically [40]
1
3
A
C
2
4
B
D
Alg2 Chapter 3.notebook
September 07, 2016
[Example 1]
An online music company offers 15 downloads for $19.75 and 40 downloads for $43.50. Each price includes the same one­time registration fee. What is the cost of each download and the registration fee?
Alg2 Chapter 3.notebook
[Got it? A]
Solve the system.
x + 3y = 5
­2x ­ 4y = ­5 September 07, 2016
x = 5 - 3y
-2(5 - 3y) - 4y = -5
x + 3(2.5) = 5
-10 + 6y - 4y = -5
x = -2.5
-10 + 2y = -5
y = 2.5
Alg2 Chapter 3.notebook
September 07, 2016
[Example 3]
Solve the system.
­x + y = ­2
(
)2 --> -2x + 2y = -4
2x ­ 2y = 0 2x - 2y = 0
0 = -4 False
There is no solution.
Alg2 Chapter 3.notebook
[Got it? B]
Solve the system.
4x + y = 6
12x + 3y = 18
12x + 3y = 18 12x + 3y = 18
There are infinitely many solutions.
September 07, 2016
Alg2 Chapter 3.notebook
[Example 4]
Solve the system.
2x ­ 3y = 14
4x + 3y = 46 September 07, 2016
Alg2 Chapter 3.notebook
[Got it? C]
Solve the system.
­2x + 8y = ­8
5x ­ 8y = 20 September 07, 2016
Alg2 Chapter 3.notebook
[Example 6]
Solve the system.
6x ­ 3y = 15
­8x + 4y = ­20 Since this is a true statement (and
there are no more variables), there
are infinity many solutions.
The solution is 6x ­ 3y = 15 (just pick
one of the equations)
September 07, 2016
Alg2 Chapter 3.notebook
[Got it? D]
Solve the system.
3x + 7y = 15
5x + 2y = ­4 September 07, 2016