Bell-work 10/14/2014
Algebra 2
Multiple Choice: Which set of ordered pairs is a solution to the system?
4x + 2y = 4
6x + 2y = 8
A. (7,5)
B. (2,4)
What type of system is this?
C. (2,-2)
D. (-1,3)
Solving Systems Algebraically
Algebra 2
Solving Systems Algebraically
Lesson 3-2
Algebra 2
Additional Examples
Use the elimination method to solve the system.
3x + y = –9
–3x – 2y = 12
–y = 3
3x + y = –9
–3x – 2y = 12
Two terms are additive inverses, so add.
Solve for y.
y = –3
3x + y = –9
3x + (–3) = –9
x = –2
The solution is (–2, –3).
Choose one of the original equations.
Substitute y.
Solve for x.
Solving Systems Algebraically
Lesson 3-2
Algebra 2
Use the elimination method to solve the system
x + y = 12
x–y=2
Solving Systems Algebraically
Lesson 3-2
Algebra 2
Additional Examples
Solve each system by elimination.
a.
–3x + 5y = 6
6x – 10y = 0
–3x + 5y = 6
6x – 10y = 0
–6x + 10y = 12
6x – 10y = 0
Multiply the first line by 2
to make the x terms
additive inverses.
0 = 12
The two equations in the system represent parallel lines.
The system has no solution.
Solving Systems Algebraically
Lesson 3-2
Algebra 2
Use the elimination method to solve the system
2a + 3b = 12
5a - b = 13
Solving Systems Algebraically
Lesson 3-2
Algebra 2
Additional Examples
On your index card solve:
b.
–3x + 5y = 6
6x – 10y = –12
–3x + 5y = 6
6x – 10y = –12
–6x + 10y = 12
6x + 10y = –12
Multiply the first line by 2
to make the x terms
additive inverses.
0 =0
The two equations in the system represent the same line.
The system has an infinite number of solutions.
Solving Systems Algebraically
Algebra 2