Warm up
Two schools opened in the same year, each with a population of 500 students.
Hillsboro High school's population increased at a rate of 160 students per
year. The population of Mountain Ridge High School increased by
approximately 20% each year.
1. On the tenth anniversary of the schools' opening, which school has the
greater population?
2. How many more students does the school with the larger population have?
Oct 8­8:13 AM
Pre-lesson:
Consider the following equation: 2x + 5y = 14
Are the following ordered pairs solutions to this
equation?
(3,5)
(2,2)
(0,7)
(-18,10)
Sep 17­3:34 PM
Solving Systems of Equations
Substitution
EQ: How do I solve 2 equations in 2 variables
through replacing one equation with the other?
Sep 3­10:21 PM
Introduction: Solve each equation for x.
1. x - 2y = 12
3. -x + y = 4
2. 2x + 3y = 6
4. -3x - 6y = 9
Sep 3­10:42 PM
What does it mean to "solve" a system
of equations?
It means that we are looking for the
solution(s) or ordered pair(s) that are
solutions to BOTH of the equations!
One way that we can solve systems of
equations is to use substitution.
Sep 17­3:29 PM
Substitution:
Step 1: Solve one equation by isolating 1
variable.
Step 2: In the 2nd equation, substitute that
variable with the expression from the first.
Step 3: Solve the 2nd equation.
Step 4: Replace the answer back in the 1st
equation.
Step 5: Write answer as a pair of
coordinates.
Sep 3­10:36 PM
Ex. A: To be put into your graphic organizer
and then in your Interactive Notebook
x + y = -2
2x - 3y = -9
Sep 3­10:29 PM
Ex. B
x + 3y = 15
4x + y = 6
Sep 3­10:29 PM
Ex. C
3x + 2y = 4
-x + 3y = -5
Sep 3­10:29 PM
Oct 9­11:32 AM