Warm Up
1. Find the solution to the given system of equations:
a)
y = ­3x + 4
4x + 2y = 1
b)
y = ­2x + 7
2x + y = 9
2. Given the equation
if y =
x = 2 3x + 5
y
, what does x = ?
Oct 12­9:39 AM
1
Find the value of x :
2x = 10
Find the value of x:
2x + 3y = 10
Oct 17­9:03 AM
2
Simplify using distributive property:
2(x + 4)
4(x-5)
1.5(x +1)
2(2x - 2)
Oct 17­9:03 AM
3
Example﴿ During a football game, the parents of the football
players sell pretzels and popcorn to raise money. They charge
$2.50 for a bag of popcorn and $2.00 for a pretzel. The parents
collect $336 in sales during the game. They sell twice as many
bags of popcorn as they do pretzels. How many bags of
popcorn do they sell? How many pretzels do they sell?
Step 1﴿ Write an equation to represent the total sales, and the
amount sold.
Step 2﴿ Solve the linear system using substitution.
Step 3﴿ Express your answer in terms of the problem.
Oct 12­9:51 AM
4
Example﴿ During a football game, the parents of the football players sell pretzels and popcorn to raise
money. They charge $2.50 for a bag of popcorn and $2.00 for a pretzel. The parents collect $336 in sales
during the game. They sell twice as many bags of popcorn as they do pretzels. How many bags of popcorn
do they sell? How many pretzels do they sell?
Step 1﴿ Write an equation to represent the total sales, and the amount sold.
Step 2﴿ Solve the linear system using substitution.
Step 3﴿ Express your answer in terms of the problem.
1.
What important information do I need to pick out?
Oct 17­9:10 AM
5
Example﴿ During a football game, the parents of the football players sell pretzels and popcorn to raise money.
They charge $2.50 for a bag of popcorn and $2.00 for a pretzel. The parents collect $336 in sales during the game.
They sell twice as many bags of popcorn as they do pretzels. How many bags of popcorn do they sell? How many
pretzels do they sell?
Step 1﴿ Write an equation to represent the total sales, and the amount sold.
Step 2﴿ Solve the linear system using substitution.
Step 3﴿ Express your answer in terms of the problem.
2.
What are the variables and equations for the situation?
Oct 17­9:10 AM
6
Example﴿ During a football game, the parents of the football players sell pretzels and popcorn to raise money.
They charge $2.50 for a bag of popcorn and $2.00 for a pretzel. The parents collect $336 in sales during the game.
They sell twice as many bags of popcorn as they do pretzels. How many bags of popcorn do they sell? How many
pretzels do they sell?
Step 1﴿ Write an equation to represent the total sales, and the amount sold.
Step 2﴿ Solve the linear system using substitution.
Step 3﴿ Express your answer in terms of the problem.
3.
Which equation should I use to substitute and why?
1.
Which equation should I use to substitute and why?
Oct 17­9:10 AM
7
Example﴿ During a football game, the parents of the football players sell pretzels and popcorn to raise money.
They charge $2.50 for a bag of popcorn and $2.00 for a pretzel. The parents collect $336 in sales during the game.
They sell twice as many bags of popcorn as they do pretzels. How many bags of popcorn do they sell? How many
pretzels do they sell?
Step 1﴿ Write an equation to represent the total sales, and the amount sold.
Step 2﴿ Solve the linear system using substitution.
Step 3﴿ Express your answer in terms of the problem.
4.
How do I do the math involved?
Oct 17­9:10 AM
8
Example﴿ During a football game, the parents of the football players sell pretzels and popcorn to raise money.
They charge $2.50 for a bag of popcorn and $2.00 for a pretzel. The parents collect $336 in sales during the game.
They sell twice as many bags of popcorn as they do pretzels. How many bags of popcorn do they sell? How many
pretzels do they sell?
Step 1﴿ Write an equation to represent the total sales, and the amount sold.
Step 2﴿ Solve the linear system using substitution.
Step 3﴿ Express your answer in terms of the problem.
5.
How do I interpret my final answer?
Oct 17­9:10 AM
9
Guided Practice
Oct 12­10:04 AM
10
Homework:
pg. 439/ 3-5
Oct 12­10:06 AM
11
Attachments
Breaking down a systems of equations word problem substitution.docx
Solving Systems of Equations substitution notes.docx