SWBAT: Solve System of Linear Equations by Substitution Method
Lesson 8-2
Do Now:
Solve the following system of equations graphically:
 −  = −2
 − 2 = 4
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SWBAT: Solve System of Linear Equations by Substitution Method
Lesson 8-2
Solving Systems of Equations by Using the Algebraic Method of Substitution
Steps for solving by substitution.
1) Solve one of the given equations for x or y. If that is already done, go to step 2.
2) Substitute the expression for x and y into the other equation.
3) Solve the resulting equation for the remaining variable.
4) Substitute the known value into either of the original equations to find the value of the
second variable.
5) C heck your solution in both of the original equations.
1)
2)
Step 1: C hoose the equation to use as the
substitute.
Step 2: Solve by substitution.
Step 3: Substitute x = 2 back into one of the
original equations to find the value of y.
Step 4: C heck
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SWBAT: Solve System of Linear Equations by Substitution Method
Lesson 8-2
3)
4)
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SWBAT: Solve System of Linear Equations by Substitution Method
Lesson 8-2
5) Mr. Lambert wants to start working out and is comparing two gym
memberships.


One gym has a $150 joining fee and costs $35 per month.
Another gym has no joining fee and costs $60 per month.
a) In how many months will both gym memberships cost the same?
b) What will that cost be?
c) If Mr. Lambert plans to cancel in 5 months, which is the better option for him? Explain.
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SWBAT: Solve System of Linear Equations by Substitution Method
Lesson 8-2
LESSON PRACTICE
# 1, 3, 6, 8, 9, 18
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SWBAT: Solve System of Linear Equations by Substitution Method
Lesson 8-2
LESSON PRACTICE
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SWBAT: Solve System of Linear Equations by Substitution Method
Lesson 8-2
Answers
Page 394 # 1, 3, 6, 8, 9, 18,
Page 396 #48, 49, 50
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