Lesson 3­3 Solving Addition and Subtraction Equations.notebook
April 03, 2017
Warm Up:
1. The scale is balanced when n + 30 = 70.
Suppose the left side becomes n + 13. How
can you change the scale so that n + 13 = ___
is equivalent to n + 30 = 70?
Complete each of the following equations to
make them true.
2. 4(9 + ___) = 36 + 28
3. 7 + 6 +11 = 13 + ___
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Lesson 3­3 Solving Addition and Subtraction Equations.notebook
April 03, 2017
Agenda:
1. Launch Question
2. Notes on Lesson 3­3 Solving
Addition & Subtraction Equations.
3. Independent Practice on Lesson
3­3 in Student Companion.
4. Error Analysis
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Lesson 3­3 Solving Addition and Subtraction Equations.notebook
April 03, 2017
Launch:
Each row, column, and diagonal in the number square has the same sum. Find the values of a, b, and c. Explain. 3
Lesson 3­3 Solving Addition and Subtraction Equations.notebook
April 03, 2017
Focus Question:
How do you use addition and
subtraction to undo each other?
Why might this be helpful in
balancing equations?
4
Lesson 3­3 Solving Addition and Subtraction Equations.notebook
April 03, 2017
Lesson 3 ­ 3
Solving Addition & Subtraction Equations
Usually, equations have an unknown
value which we have to discover.
equation ­
Remember that we use variables to
represent unknown values.
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Lesson 3­3 Solving Addition and Subtraction Equations.notebook
April 03, 2017
Lesson 3 ­ 3
Solving Addition & Subtraction Equations
When you solve an equation, your goal
is to get the variable alone on one
equation ­
side of the equal sign.
How would we solve for x in the balance
scale below?
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Lesson 3­3 Solving Addition and Subtraction Equations.notebook
April 03, 2017
Lesson 3 ­ 3
Solving Addition & Subtraction Equations
Example 1: How many comic books do you need to
add to the 17 comic books you already own to
have a total of 30 comic books? Solve the equation
17 + x = 30, which models the situation.
üCheck: 7
Lesson 3­3 Solving Addition and Subtraction Equations.notebook
April 03, 2017
Lesson 3 ­ 3
Solving Addition & Subtraction Equations
Vocabulary:
equation ­Operations:
Inverse
Operations that undo each other.
Addition and subtraction are inverse
operations.
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Lesson 3­3 Solving Addition and Subtraction Equations.notebook
April 03, 2017
Lesson 3 ­ 3 Solving Addition & Subtraction Equations
Example 2: Each equation shows an operation.
Drag each equation to the inverse operation of the
operation shown.
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Lesson 3­3 Solving Addition and Subtraction Equations.notebook
April 03, 2017
Lesson 3 ­ 3
Solving Addition & Subtraction Equations
Steps in Solving for a Variable:
1. To find the value of a variable such as h, you
need to get h by itself on one side of the equal
sign (this is called isolating the variable).
2. To isolate the variable, use the inverse (or
opposite) operation. Inverse operations "undo"
each other.
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Lesson 3­3 Solving Addition and Subtraction Equations.notebook
April 03, 2017
Lesson 3 ­ 3 Solving Addition & Subtraction Equations
Example 3: Solve each of the following equations.
a.) ü Check:
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Lesson 3­3 Solving Addition and Subtraction Equations.notebook
April 03, 2017
Lesson 3 ­ 3 Solving Addition & Subtraction Equations
Example 3: Solve each of the following equations.
b.) ü Check:
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Lesson 3­3 Solving Addition and Subtraction Equations.notebook
April 03, 2017
Lesson 3 ­ 3 Solving Addition & Subtraction Equations
Example 3: Solve each of the following equations.
c.)
ü Check:
d.)
ü Check:
13
Lesson 3­3 Solving Addition and Subtraction Equations.notebook
April 03, 2017
Focus Question:
How do you use addition and
subtraction to undo each other?
Why might this be helpful in
balancing equations?
14
Lesson 3­3 Solving Addition and Subtraction Equations.notebook
April 03, 2017
Classwork:
1. Pg. 66 ­ 67 in Student Companion
2. Error Analysis ­ Identify the error in solving the equation, then correct it. Record your answer in your math notebook.
Error Analysis:
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