Academy Algebra II
3.1: Solve Linear Systems by Graphing
HW: p.156 (4, 8, 10, 12), review old
graphing: absolute value, quadratics, etc.
Quiz 3.1, 3.2: Friday
10th graders: Ch 3 Test: Wednesday, 3/4
9th graders: Ch 3 Test: Monday, 3/9
How to solve linear systems
graphically.
 Graph
both lines in the same coordinate
plane.
 Your solution is the ordered pair where the
two lines intersect.
 What would be the solution if the lines
do not intersect?
 What would be the solution if the lines
overlap each other?
Find the solution to the
system graphically.
y = -3x – 2
3x + 2y = 2
Find the solution to the
system graphically.
2.) y = 2
x = -4
3.) 2x + y = 4
-4x - 2y = -2
4.) y = -1
3x + y = 5
Find the solution to the
system graphically.
2x + y = 4
-4x - 2y = -2
Find the solution to the
system graphically.
y = -1
3x + y = 5
Academy Algebra II
3.2: Solve Linear Systems Algebraically
HW: 164 (28-38 even), p.182 (10, 18)
Quiz 3.1, 3.2: Friday
10th graders: Ch 3 Test: Wednesday, 3/4
9th graders: Ch 3 Test: Monday, 3/9
What are the two algebraic methods of
solving a system of equations?
 Substitution
 Elimination
(linear combinations)
Solve the system using the
substitution method.
2x + 5y = -5
x + 3y = 3
Solve the system using the
elimination method.
3x – 7y = 10
6x – 8y = 8
Academy Algebra II
3.2: Solve Linear Systems Algebraically
HW: p.164 (28-38 even), p.182 (10, 18)
Quiz 3.1, 3.2: Friday
10th graders: Ch 3 Test: Wednesday, 3/4
9th graders: Ch 3 Test: Monday, 3/9
3.4: Solve the system.
4x + 2y + 3z = 1
2x – 3y + 5z = -14
6x – y + 4z = -1
Solve the system using the
substitution or elimination method.
1.) 4x + 3y = -2
x + 5y = -9
2.) 3x + 3y = -15
5x – 9y = 3
3.) 3x – 6y = 9
-4x + 7y = -16
4.) 12x – 3y = -9
-4x + y = 3
Solve the system using the
substitution or elimination method.
3.) 3x – 6y = 9
-4x + 7y = -16
4.) 12x – 3y = -9
-4x + y = 3
To raise money for uniforms, your school sells
t-shirts. Short sleeve t-shirts cost $5 each and are
sold for $8 each. Long sleeve t-shirts cost the
school $7 each and are sold for $12 each. The
school spends a total of $2500 on t-shirts and
sells all of them for $4200. How many short
sleeve t-shirts are sold?
p.165 # 55
In one week, a music store sold 9 guitars for a
total of $3611. Electric guitars sold for $479 each
and acoustic guitars sold for $339 each. How
many type of each guitar were sold?